I would start by just deleting that character's .ini from your macro folder and letting it recreate it when you fire it up. This is pretty straight forward. From the VeryVanilla tab on RG Launcher click Open MQ Folder - Macros - Rgmercs - PCinis - Your character name will be on the end of the file you want to delete --- Don't worry, it will immediately recreate it as default when you start it next time.
Make sure you have the tank set as main assist (bard and zerker assisting, so you're probably fine there). Make sure you have whatever spells its spitting out at you that it needs when you first start it.
Each time you start RGmercs on any character, make sure you are targeting whoever your main assist is, as well. It uses the in group roles for various things, but this is generally best practice. If you ever start using
KissAssist at all you'll need to do this as well, and you'll already have been doing it so it won't be an adjustment. Just add a line in a social for it - Example being pressed from character, but you can broadcast this through EQBC, of course.
/target YourMA Name
/pause 15
/rgstart
After you let it recreate your ini, make sure your assist percent isn't set too low. By default it should be pretty high, so that shouldn't be it, but just double check.