I have to replace the cushion snap in my denture 3 x yr or the denture doesn't stay snapped in. Any suggestions?

I want to be able to buy the plastic snaps and insert myself avoiding the dental office expenses as I am living on SS income only. I thought once I got the snap in denture that was it....I didn't realize I had to go repeatedly back to have the snaps replaced. This is definitely a CON to this snap in denture. I know it must be a pretty easy procedure and that you may have to have certain tool. joan