Understanding EA Settings: Complete Config Guide
The most important EA settings to configure are: lot size/risk percentage (position sizing), stop loss (loss protection), take profit (gain locking), and magic number (trade identification). Start with the developer's default settings and only adjust lot size to match your account. Access settings via right-click chart > Expert Advisors > Properties > Inputs tab.
Configuring your Expert Advisor correctly is the difference between a profitable EA and an account-destroying one. I have seen traders take a perfectly profitable EA and ruin it by changing settings they did not understand. This guide covers every EA setting you will encounter, explains what each one does, and tells you which ones to change and which to leave alone. Whether you are setting up Golden Viper EA or any other Expert Advisor, these principles apply universally.
In This Guide
How to Access EA Settings
There are two ways to access your EA's input parameters on MT4/MT5:
Method 1: When First Attaching the EA
- Drag the EA from the Navigator window onto a chart
- The properties dialog opens automatically
- Click the Inputs tab to see all configurable parameters
- Modify values and click OK to start the EA
Method 2: While the EA Is Running
- Right-click the chart where the EA is active
- Select Expert Advisors > Properties
- Click the Inputs tab
- Change values and click OK (EA restarts with new settings)
Core Settings Explained
These are the settings every EA has in some form. Understanding them is essential before going live:
| Setting | What It Does | Typical Default | Should You Change? |
|---|---|---|---|
| Lot Size | Fixed position size per trade | 0.01-0.10 | Yes -- match to your account |
| Risk % | Auto-calculates lot from balance | 1-2% | Yes -- match your risk tolerance |
| Stop Loss | Maximum loss per trade (in pips) | Varies by EA | Usually no -- keep default |
| Take Profit | Target profit per trade (in pips) | Varies by EA | Usually no -- keep default |
| Magic Number | Unique ID for the EA's trades | Random/set by developer | Only if running multiple EAs |
| Max Spread | Maximum spread to open trades | 30-50 points | Rarely -- lower if ECN broker |
| Slippage | Maximum allowed slippage | 3-10 pips | Rarely |
Lot Size vs Risk Percentage
Most EAs offer either fixed lot sizing or risk-based auto lot sizing. Choose one:
- Fixed lot: Same lot size every trade regardless of account balance. Simple but does not scale.
- Risk percentage: EA calculates lot size based on your balance and stop loss distance. Scales with your account. Recommended for most traders.
For detailed lot size calculations by account size, see our position sizing calculator.
Risk Management Settings
Stop Loss
The stop loss is your maximum acceptable loss per trade. Never disable it. An EA without a stop loss will eventually blow your account during a Black Swan event or flash crash.
- Fixed stop loss: Set distance in pips (e.g., 300 pips for XAUUSD)
- ATR-based stop loss: Adapts to current volatility using Average True Range
- Percentage-based: Closes if loss reaches X% of the trade's value
Take Profit
The take profit is your target gain per trade. Some EAs use fixed take profit while others use dynamic exits based on indicators or trailing stops.
Trailing Stop
A trailing stop moves your stop loss in the direction of profit, locking in gains as the trade moves favorably. Settings typically include:
- Trail start: Minimum profit before trailing begins (e.g., 100 pips)
- Trail step: How frequently the stop moves (e.g., every 10 pips)
- Trail distance: How far behind the current price the stop sits
Maximum Drawdown
Some EAs include an emergency stop that halts trading if account drawdown exceeds a threshold (e.g., 20%). This is an excellent safety feature. Set it to a level you are comfortable with -- typically 15-25% of your account.
Advanced Settings
Session Filters
Many gold EAs allow you to restrict trading to specific sessions. For XAUUSD, the most profitable sessions are London (08:00-16:00 GMT) and New York (13:00-22:00 GMT). Limiting trading to these sessions reduces exposure during the low-liquidity Asian session where spreads widen. Learn more in our gold trading hours guide.
News Filters
Some EAs can detect high-impact news events and pause trading to avoid volatility spikes. This is valuable for gold EAs because XAUUSD reacts violently to Fed decisions, NFP, and CPI data.
Magic Number
The magic number is a unique integer that tags every trade the EA opens. It is critical when running multiple EAs on the same account:
- Each EA must have a different magic number
- If two EAs share a magic number, one may close the other's trades
- Set to 0 only if the EA should manage manually opened trades (rare)
Settings Mistakes to Avoid
| Mistake | Consequence | Prevention |
|---|---|---|
| Disabling stop loss | Unlimited loss on any trade | Never set stop loss to 0 |
| Risk percentage too high | Account blown during losing streak | Keep at 1-3% maximum |
| Same magic number on two EAs | EAs interfere with each other | Assign unique numbers |
| Changing strategy parameters | Breaks the tested edge | Keep indicator periods at defaults |
| Wrong timeframe | EA logic does not match chart | Use the developer-specified timeframe |
| Max spread too low | EA never opens trades | Set above broker's typical spread |
Golden rule: If you do not understand what a setting does, leave it at the default value. EA developers optimize these parameters through extensive testing. Random changes almost always make performance worse. If you want to optimize, use the Strategy Tester first.
Recommended Configurations by Account Size
| Account Size | Risk % | Approx Lot (XAUUSD) | Max Open Trades |
|---|---|---|---|
| $500 | 2% | 0.03 | 2-3 |
| $1,000 | 2% | 0.07 | 3-4 |
| $5,000 | 2% | 0.33 | 3-5 |
| $10,000 | 1-2% | 0.33-0.67 | 3-5 |
| $25,000+ | 1% | 0.83+ | 3-5 |
These are starting recommendations. Adjust based on your EA's specific stop loss size and your personal risk tolerance. For complete risk management strategies, read our risk management guide.
Frequently Asked Questions About EA Settings
What are the most important EA settings?
Lot size or risk percentage (position sizing), stop loss (loss protection), take profit (gain locking), and magic number (trade identification). Get these four right and your EA will function safely.
What is a magic number in EA trading?
A unique identifier an EA assigns to its trades, allowing multiple EAs to run on the same account without interfering. Each EA needs a different magic number to prevent one from closing another's trades.
Should I change the default EA settings?
Only change lot size or risk percentage to match your account. Keep strategy parameters (indicator periods, stop loss distance, etc.) at defaults unless you have backtested changes thoroughly.
What risk percentage should I set?
1-2% for conservative, 2-3% for moderate. Never exceed 5%. Most professional EA traders use 2% per trade for balanced growth and safety.
How do I access and change EA settings on MT4?
Right-click the chart > Expert Advisors > Properties > Inputs tab. Modify values and click OK. The EA restarts with the new settings immediately.