If the selectors for your options are greyed out, then the list you're looking at is using Shared Settings. You should see an alert at the top of the page telling you so.
If you are an account administrator, you may wish to edit the Shared Settings. To do so, click the "edit Shared Settings" at the top of the page. If you want to change the settings for this list, without changing the settings for all other lists that use Shared Settings, you can set this list to use its own individual settings. Just go to List Policies and switch "Share Settings with Other Lists" to Individual List Settings.
If you are a listowner, you cannot edit shared settings. You can view the settings for this list, and edit the settings that are not shared, but you cannot edit them. If these settings need to be changed, please contact an account administrator to make the changes for you.
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