Haha, absolutely relatable. As others have suggested, you should keep an ideas journal. The brain tends to replay things that it wants to remember. Once you write it down, your brain will (theoretically) think about it less often because it knows the knowledge is stored safely somewhere. It also helps you sort out which ones you'll really care about versus the ones that just seem super cool right now.
I also have a private side project of "snippets" that I just can't get out of my head. For instance, if I have an exceptionally cool character design idea, or a great scene that I can't wait to write, I'll draw that one design or write just that scene. I don't post it anywhere, but it helps get that energy out without having to design every other character, or write every scene that leads up to the one I really like. And hey, if I get around to doing that project for real someday, I already have a head start.