Expert Advisors Tab
Settings of working with Expert Advisors are grouped in this tab. Expert Advisors in the terminal are programs written in MetaQuotes Language 4 and allowing to analyze and trade in the automatic mode (auto trading). The description of how to create and use experts is given in the "Auto Trading" section. The given section describes only settings common for all experts:

Enable Expert Advisors
This option allows to enable or disable the use of all expert advisors. If it is disabled, the start() function will not run for all expert advisors when a new tick incomes. At that, daggers will appear instead of smileys opposite the names of experts in the upper right corner of the chart. To enable expert advisors, it must be enabled and the "OK" button must be pressed. As soon as a new tick incomes, expert advisors will start working, and daggers in the upper right corner of the chart will become smileys again.
Experts can be enabled or disabled by pressing of the of the "Standard" toolbar.

Attention:
This option is intended only for expert advisors, and it does not allow to disable custom indicators and scripts automatically.
This option does not influence any experts already running, i.e., an expert will not be stopped during its execution of the start() function.
Disable experts when the account has been changed
This option represents a protective mechanism disabling expert advisors when the account is changed. It is useful, for example, when one changes demo account for a real one. For the mechanism to be enabled, it must be enabled and the "OK" button must be pressed.

Disable experts when the profile has been changed
A large amount of information about the current settings of all charts in the workspace is stored in profiles. Particularly, profiles contain information about experts attached. Experts included into the profile will start working when a new tick incomes. Having enabled this option, one can hinder the experts launching when the profile has been changed.

Allow live trading
Expert advisors are able to work independently, without any trader's participation. They can both analyze the price changes and trade. This option is intended for limitation of trading performed by experts. This limitation can be useful to test analytical capacity of an expert in the real-time mode (not to be confused with testing of expert advisors on history data).

Manual confirmation
The "Manual confirmation" option is enabled only if live trading is enabled for expert advisors. If manual confirmation is enabled and expert attempts to perform a trade operation, it will be possible to confirm it or to interrupt manually. In other words, manual confirmation allows to control the trading activity of the advisor. At that, the window of trade operations with all fields filled out appears. This can be useful for testing the expert advisor trading functions in the real-time mode (not to be confused with testing of expert advisors on history data).

Allow DLL imports
To enlarge their functionality, expert advisors can use DLLs (dynamic-links libraries). If it is enabled, such libraries can be used without any limitations. If this option is disabled, no expert can use external DLLs. It is recommended to disable import when working with unknown experts.

Confirm DLL function calls
This option will only be enabled if DLL imports have been allowed. It allows to perform manual control over execution of each function called. If it is disabled, import from external DLLs will not be controlled. It is recommended to enable this option when working with unknown libraries.

Allow external experts imports
If there is a need to import functions from other experts or MQL4 libraries during the expert advisor operation, this option must be enabled. If it is disabled, no one of the running experts will be able to request functions from other MQL4 programs. It is recommended to disable this option when working with unknown expert advisors.

Attention: Values of options named "Allow live trading", "Ask manual confirmation", "Allow DLL imports", "Confirm DLL function calls", and "Allow external experts imports" specified in this window are default parameters for MQL4 programs newly attached. They do not influence the operation of expert advisors? custom indicators and scripts already running.