If you are only going to be using the CUI interface but want the user defined mode there reset to 50%, the simplest way is to enter the FUI and then exit back to the CUI. You do not have to do anything in the FUI, except to switch back to the CUI. Your user defined mode is now back at 50 percent.
To switch between interfaces, do 5C+PH. Repeating the 5C + PH will switch you back to the interface you started with. If you want to retain that 50% setting, just be careful never to ramp in the user defined mode. Instead, if you should temporarily want a different level, switch to either Min or Max and do your ramping there where the ramped levels are not retained.