I have a couple of old oyster passes from 2 years ago that have balance remaining. If I'm not mistaken they were on zones 1-4. Is there any way to find out what the balance on the card is and to increase the zones to 1-9 while I'm in the States before I travel
Oyster cards are not restricted to zones. You can use them in any zones.
You can find out the balance on the cards and top them up at any tfl station. There is no real need to do anything before you are back in London. They should work with no problems.
You can check balance and load money (or travelcards) via the TfL Go app. Although this is geoblocked it may be defeatable with a suitable VPN.