For some reason my R5 camera is stuck/locked on F/4.0. I used to be able to change it by rotating the 'Back' wheel. It has stopped doing that and I have found no way to correct it. Even resetting camera does nothing.
Which shooting mode are you in? Sounds like your in a auto mode that is not allowing you to adjust the aperture... In aperture priority it will select the shutter for you based on the aperture you select. The opposite is true for the Shutter priority which may be what you are in if your not in some other auto mode. On my cameras, I usually am in full manual where i use a dial for each of them and control over and under exposure myself. https://cam.start.canon/en/C003/manual/html/UG-02_ShootingMode_0070.html
I apologize for not making it clear that I am not greenhorn photographer. In fact, like you I shoot 99% of the time in manual. At that time the back wheel was used to adjust the camera f/stop. Thank for the reply. Jerry
