I have two batteries on the boat, is it better for me to charge them individually or is it ok for me to turn the battery selector to " ALL" and in a sense charge both batteries at the same time??
That is part of what the all position is for.
The automatic charge relays, voltage sensitive relays, or whatever you call them does exactly that when the voltage reaches a certain voltage on your main battery, it parallels the two batteries together to charge at the same time.
You should have one of these if you are talking about an onboard charger,called a smart charger.It moniters both battery's and only charges what is needed for each battery. If you have one charger hooked to one battery,it will cook the one that is fully charged! GUEST ChargePro Weather-Resistant Battery Chargers at West Marine
Grub
What I was refering to as a charger is a 12V portable battery charger. If I havent takent the boat out for a while and I want to make sure that the batteries are at 100% before I go I want to charge them up is it ok to just place the battery selector switch to "ALL" and then just hook up the battery charger to one of the batteries, will it charge up both batteries at the same time or is it better to just charge them one at a time.
