A script performs a task when you launch it; it is not the same as a continuously running EA. These instructions apply to desktop MT4, not FXTRADING.com App or Web Trader.
Before you launch
Use a script whose purpose and source you understand. Start with a Demo Account and confirm the account, full symbol and chart timeframe.
A script can place or close trades as well as analyse data. Launching it is an action, not a preview. Do not test unfamiliar scripts on an account holding money you need to protect.
Open the script and review its settings
Choose View → Navigator, or press Ctrl+N. Expand Scripts and identify the intended installed MT4 program.
Select the intended chart. When ready to run the program, drag the script onto that chart, or use Execute on Chart from its context menu. Double-clicking attaches it to the active chart.
A settings window appears only if the script is designed to show one. Otherwise it can start immediately. Do not assume there will always be another confirmation.
If settings appear, review Common permissions and the Inputs values. Double-click a value to change it. Reset restores defaults; Save stores an input set and Load retrieves one. Check the resulting values rather than relying on a preset filename.
Choose Cancel to abandon that launch, or OK only after checking the account, chart, permissions and inputs. Script-specific properties are set at launch.
Understand trading and external-access permissions
Terminal-wide automated-trading settings and the script's own trading permission both matter. Check Tools → Options → Expert Advisors and any Common settings shown for that launch.
The AutoTrading toolbar control can block automated trading operations while a program continues other work. It does not undo an order already sent.
DLL imports and WebRequest website access are separate permissions. Do not enable them merely to clear an error. Allow only access required by a program and destination you have independently decided to trust.
Stop a script that is still running
Right-click its chart and choose Remove Script while that command is available. A script normally finishes by itself, so the command may already have disappeared.
MT4 allows one script per chart. Attaching another, changing that chart's symbol or timeframe, or shutting down the terminal removes the running script. Use Remove Script to stop it without launching a replacement.
Deleting its name from Navigator does not stop an instance already attached to a chart. Stopping the program is not a reversal of actions it has already completed.
Check the outcome before trying again
Review open positions and pending orders in Terminal → Trade, and completed records in Account History. A missing script or closed settings window alone does not prove the intended task succeeded.
If the outcome is unclear, check the program's messages and relevant logs before launching it again. Repeating a one-off trading script can repeat its action. Keep passwords and other private account information out of diagnostic material.