The screen display options are buried in the set-up menu.
The 10 Items that can be made "Available for Customization" to the Quick Control Screen are identified in the chart included in the EOS R5 Advanced Manual (V.2) under "Operation" pp. 821. Some functions may only be visable if Enabled using other, previously selected menu functions. The QC Screen content & layout may change dynamically depending on your operating/viewing mode. Some items are always present, and apparently can't be removed.
The R5 is one of the most 'customizable' image-capture computers made today. Unfortunately, not many of us will have the memory retention ability to recall all the customization settings we might apply. Thank goodness there's a reset to factory settings option.
Hope this helps.
12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.