What the button does
The AutoTrading button is a master switch that allows expert advisors (automated programs) to place trades on your behalf. When it is off, EAs are loaded but cannot trade; when it is on, they can. It is a single global control that overrides everything.
Because an EA can trade real money automatically, this button is the most important safety control in the platform. Knowing how to turn it off instantly is more valuable than knowing how to turn it on.
The numbered steps
Step 1: Find the "AutoTrading" (MT5) or "AutoTrading"/"Expert Advisors" (MT4) button on the top toolbar — a prominent button that turns green when active and red when off.
Step 2: Click it once to enable. It should turn green, and any EA on a chart should show a smiling face rather than a sad or crossed-out one in the chart's top-right corner.
Step 3: Confirm in the chart corner: a green ▶ or smiley next to the EA name means it is allowed to trade; a red ■ or frown means it is not.
Step 4: To stop everything at once, click the AutoTrading button again. It turns red and no EA can place a new automated trade — this is your emergency stop.
Common reasons an EA still will not trade
If AutoTrading is green but the EA still shows a frown, check the EA's own "Allow Algo Trading" setting in its properties, make sure the market is open, and confirm the EA is attached to the correct chart. On MT4, the older setting "Allow live trading" must also be ticked in the EA properties.
It is worth confirming all of this on a demo account, where an EA misbehaving costs nothing.
An honest risk note
With AutoTrading on, an EA can open and close real positions without asking you, as fast as the market moves — including while you are asleep. A buggy or malicious EA can do serious damage quickly. Never leave an untested EA running on live money, keep the AutoTrading off switch within reach, and check on any running EA regularly rather than trusting it blindly.