Help AR Deposit given me a PP out of nowhere.

I go to cash receipts entry and I double click. I created a new batch I click accept, then I created a new deposit number I type the total deposit amount and click accept, then I look for the customer number hit tab then I type check# then I type the check amount, then I go to the second tab and I select invoice or invoices from the little icon that brings the window with the customer open invoices, once i see the invoice the customer is listing on the check  I select the specific invoice (depending on the check amount) the system does the rest and applies the check amount to the invoice balance.

Here is my problem, I noticed yesterday that two customers (LAWRENCE TOM one of them) sent a check with less money than the invoice amount. Example: the invoice was 342.43 he paid he paid 242.43...I selected the invoice 242.43 was posted and 100 were left on the unposted invoice line column. my question is how in the world a PP was created?

I ran a Deposit report this is how the cash deposit reports look like now:

I didn't do all those PP I just started to post deposits two weeks ago, but whatever is triggering them is messing up with the Customer aging and balances. Why sometimes the PP comes in negative? why sometimes shows in positive, why sometimes shows a balance? I'm sure I did all right on 2/6 and 2/8 (the only two days I posted and the PP shows) I WAS POSTING DEPOSITS ONLY THOSE DAYS and the system didn't ask me if I want to do a PP or not I ever press PP in any of the instances to create a PP invoice.

This morning my new boss blamed my fingers and fixed "Medical Center" no idea if the fixed shows on this report. Then I post for the 2/28 and I ran this report. What are we doing wrong?

Check Number DEPOSIT NUMBER Customer Name Invoice Applied Date            Number Balance
VISA 1/3/19 15316 0024031 ACTION SUBRENTAL PP-PP -5749.29 0 0 0
  1/7/19 15359 0021728 HAMMOCK FISH CAMP PP-PP 329.35 0 -329.35 0
7476 1/28/19 15459 0024459 EASTBROOKE GARDENS INC PPPP-PP 100 0 0 0
  1/14/19 15386 0012213 JAMES K MANN PP-PP -20 0 0 0
  1/18/19 15422 0012213 JAMES K MANN PP-PP 20 0 0 0
  1/14/19 15396 0024428 KEEP IT GREEN  PP-PP 545.1 0 0 0
6510 B 2/8/19 15523 0067571 LAWRENCE TOM PP-PP -100 0 0 0
7373 B 2/8/19 15523 0041419 LILYAN SUREZ PP-PP -109.92 0 0 0
  2/6/19 15504 0022019 MEDICAL CENTER PP-PP -2119 0 0 0
  2/6/19 15516 0022019 MEDICAL CENTER PP-PP 2119 0 -2119 0
  2/6/19 15504 0024122 Pet SITE SERVICES P-PP 1041.11 0 0 0
  1/15/19 15394 0024452 SITE FUEL USA, INC. PP-PP 166.22 0 0 0