Hi,
I'm attempting to add flags to any of my tickets on any project. In my previous company, I would click here, and find the option to add a flag and see my ticket highlighted before.
I would like this ability in my new jira.
I can see the custom field 'flagged' is locked, and it has a default screen (which is associated to all my projects), please see below Flagged ticket information:

The context seems okay, as you can see below it says it's applied to all the issues of any type:
On find my field it seems ok:

Although the global settings seem fine, in my project settings->issue layout, when I add 'flagged' in to any of the section (descriptive/context or view when hidden area), it will stay, until I save. Then it will go back to Field list (as if I didn't assign it to my jira). Please see below:

Also just for some further context, I've added it in my screen where I should expect to see it for all projects:

Sorry if this was confusing, I just wanted to give some context to the situation!
Many thanks,
Ahmed