Can't Change Frame Rate in Project - FCPX 10.4
I'm new to editing with a professional program and just got FCPX about a month ago, so pardon if I'm asking a stupid question...
So, I shot a 23.98 interview and I've been cutting it into several short videos. For some reason, each of the projects I've created is 30p. Perhaps I started the first project off with some 30p b-roll or a JPG (though I don't think I did that), and I've duplicated each project to create the next one, since they're all structured similarly. So even projects with no 30p material at all are 30p.
I understood, however, that none of that mattered, since I could easily change the project settings (including frame rate) whenever I wanted. Only problem is, when I select any of my projects and click the blue MODIFY button to get to that window, 30p is the only possible choice for frame rate. I should mention that FCPX allows me to change the other settings in this window (format, resolution, etc.).
Am I doing something wrong or is there a bug with FCPX? I am running FCPX 10.4. Thanks for any help!
MacOS Sierra 10.12.6
27" iMac (Late 2012)
3.4Ghz i7 processor
32GB RAM
macOS Sierra (10.12.6)