Autostart command-line parameters

Some programs require command line parameters to control behavior. How to I edit an autostart command-line? For example the start program won’t start minimized & return to minimized unless you change the command to:
signal --start-in-tray

Note that entering in as an autostart command seems to do nothing at all.

In your .desktop file suggest surround the command with a call to sh i.e.

 Exec=sh -c "myapp --aparameter parametervalue %F"