You can also track balances on the Disney GC website if you enter your cards and manage them there.
It’s also a good idea to keep an extra GC with a small balance on hand just in case you lose one. Just transfer the balance and you’re good as new.
I had to do this once when I foolishly paid for lunch, threw the GC on the tray, buried it beneath a few napkins and then tossed it in the garbage with the rest of the trash. Vacation brain at its best
The balance is on any receipt. But, my GC can be very large amounts & a few CM's have seen the folly in announcing how much is on my card (which is essentially cash), its not wise to announce loudly how much cash you're carrying. I prefer when they circle the amount or simply state the balance is on the receipt