Question When I press one button, i.e. FILTER, the COMP button switches on simultaneously. Is there a link function somewhere

This may happen if you have configured two switches to control the same parameter. This can happen by mistake when editing the Switches menu. To solve the problem, press EDIT / MENU and go to the Switches menu. Check with the page encoder that each Switch has its own function.  Probably two of them are set up to control the same parameter.