How can I adjust my bottom flipper?

[Lucas]

I was born missing one tooth (the tooth to the left of the middle two), and so when my orthodontist gave me braces, he also used them to create a space for a fake tooth. That tooth just sat on the braces but when I got the braces off, I got given a bottom retainer with one tooth attached to it, and two little metal pieces sticking out on both sides. I think it's called a flipper. At first this fit fine, but recently it became extremely loose in my mouth, and pretty much just rests on my gums. The metal pieces are offering no tightness for the tooth. The last time I went to see my orthodontist, he told me there was a way to tighten the retainer myself, and it involved adjusting the metal pieces. So far, i have had no luck, however, I manipulate the metals. Is there something I'm doing wrong, or any way to tighten the retainer without going in to see my orthodontist every time? Any help would be much appreciated.