"I talked to someone that told me to keep the aux battery switch off while I'm connected to shore power because it over charged the battery?
You don't provide any information about your MH. The "aux. battery switches" I've seen are the intermittent contact type meaning that the chassis battery will only be manually interconnected to the coach battery(s) while you press the (usually a rocker type) switch. Yours may be different, but you need to be clear on what type of switch you have. Most batteries (coach to chassis) are automatically interconnected by a solenoid whenever the chassis engine is running but NOT when connected to shore power. (engine off)
Chum lee