If you have a check returned for insufficient funds, you can post the check amount back to your customer's account and also charge a returned check fee.
To post a returned check, click on Post Payments, then click on Other. You will see the Post Returned Check option. Click on this.

You will see the screen below. Select the account you want to post to from the drop-down customer list.

The customer information will appear.
Check Number - Enter the check number that was returned by the bank.
Post Date - This is the date you want it posted back to their account.
Amount - Enter the amount of the check.
Reason for Return - Put a brief message here for reference only. "Insufficient Funds" or "Closed Account"
Return Fee $ - If you charge a fee on all returned checks, enter the amount here. This will be posted to their account when you run the end of day report final.
Once you have filled in all of the fields, click on Post to Account button. Once this is posted, it can't be reversed. You can only post a payment to it to remove it.