Hi @ProtoSup ,
I did some additional research here and the 'Run only users' is available only for manual triggered flows. So you won't actually need to edit this setting in your flow, assuming that it has a recurrent or automated trigger.
Just to confirm: are you able to see this 'Share' button in your Code Editor, when clicking in the 'Script' ellipsis?

Also, if you are using your Excel in the Desktop App, could you please try these alternatives with Excel for Web?
Let me know if it works!!