R5 Defulting to FHD, is there a way to lock it?

[Bre0013]

My R5 keeps switiching video record quality from 4k-D to FHD. Is there a way to lock this setting so it can't be changed? Im using a custom mode so it really shouldn't be changing when I turn the camera on/ off.

It's happening while in an underwater housing, so it's not like I'm accidentally changing it on the touch screen. Very frustrating mid shoot!

[p4pictures]

When using custom shooting modes, they don't retain any changes in settings that you make after storing registering the custom mode. However this default behaviour can be overridden. From the menu where you register the custom shooting modes, you will find a setting for Auto update set. and it is disabled by default, but if you enable this, then when you make a change to a setting in the custom mode, the custom mode is updated with the changed setting. You can then if you wish turn the auto update set. off. 

So if you store a custom mode, say to C1. Then switch to the C1 mode and make a change to 4K-D it will be lost when you switch to another mode or the camera is powered off. But if you allow the custom mode settings to be updated then it will be retained, similar to how it works in the regular P/Tv/A/M/Fv modes. 

See this part of the manual, and read the section headed Automatic Update of Registered Settings.

https://cam.start.canon/en/C003/manual/html/UG-07_Set-up_0300.html