TradeStation Help
To enter a command in the Command Line, it is not necessary to place your pointer in the Command Line; any typing in the active window is automatically entered in the Command Line as a potential command. However, commands are not executed until you press ENTER.
The Command Line provides a drop-down list containing any previously used commands. You can select one of your previous commands from the drop-down list and press ENTER to execute it.
to insert last used symbols and selected intervals or click Symbol Lookup 
to search for symbols by name or description.