Customer NSF - without Accounting

apply NSF as a negative  amount - this will add a positive account balance and put the negative in the deposits.  Deposit the negative amount by itself on the day it came out of your bank account.
If you are going to charge an NSF fee, insert the record on the customer's account (Customer Files, F8 A/R,  F2 New).  Put the fee amount in the charge column, press F9 EXT, and on the bottom GL distribution column - left side, you can choose a gl to post that amount to using the drop down. The amount needs to be entered directly to the right of the gl.