So 1 of the 4 places you can set permissions to make a payment you can click properties then select the folks or groups that you want to be able to accept a payment and then click ok after you choose group and then ok at bottom and I believe usually it will happen you close and reopen TSS usually when you click ok the second time.  This is one is labelled Main Screen or MainForm - Accept an Invoice Payment

Next Number two spot in App settings Security where you can set permissions for accepting a payment is

in the Invoice Section Make a payment to an invoice here again choose properties and check the boxes for the groups you want to be able to accept a payment

Number 3 place in the App Settings Security to set permissions for invoice payments is

Payment Screen New again do properties and check the boxes for the groups you want to allow payments 

Number 4 place within app settings security to set permissions for making a payment is 

Invoice Screen Accept Payment