IF I close the books can I go back with an adjustment is necessary

Good to see you here in the Community, useraccounts31.

Yes, QuickBooks allows us to go back to a closed book and make necessary adjustments. 

If you need to know more about how closed books work, the following resources are good references. On the same link, we can find details on how to track the changes after closing the books:

Edit your closed books.

Close your books in QuickBooks Online.

Should you need additional help, please let me know. I'm always willing to lend you a hand.