09-27-2021 05:25 AM
How custom modes behave is 100% dependent upon what settings and shooting mode that you have stored into them.
If you have not stored any settings into a custom mode, then that could be a problem.
09-27-2021 05:49 AM
I just cleared all my settings for the custom mode to check if that might solver the problem but I can still only change the appature, and the shutter speed and iso remain locked.
I can't seem to find a setting or mode to change that
09-27-2021 07:39 AM
Choose manual mode, set your ISO, shutter speed, and aperture to the desired setting. Then go into the menu and register to C1, C2, or C3 and it should store all of them together. ISO can be stored as auto.
It sounds like you were in aperture priority mode when you tried to set things up. I haven't used a R5 but in my 1DX series bodies there is an option as to whether changes made while in one of the C1, C2, or C3 modes will remain or revert back to saved once you exit the mode. The R5 may have similar custom configuration settings that impact how the custom modes behave but the basic setup for storing in custom mode should be done in manual exposure mode if you want full control over all three legs of the exposure triangle.