Can't edit some of the custom fields such as country

Hi team,
I was trying to change the country custom field to limit the selection to one country, but it looks like this feature is locked. I find this is happening for some other fields such as city, zip code and more.
What's up with that? Can you clarify how to unlock this?
Thanks,

 

Please ignore this request. There must have been a glitch somewhere, but it is working now after I restarted my computer. Sorry about that.