SharePoint "Add items" permission is allowing editing. How do I stop it

In SharePoint, I want users to add items but not be able to edit or delete them after. The "add item" permission shows "edit" not checked (i.e. so they should 开发者_JS百科not be able to edit) However, they can. Any suggestions?

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Are you testing as a site collection admin? they ignore permissions

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SharePoint works on a highest permissions policy so if a user is in 2 groups which have permissions to the list and one group can edit but the other group cannot, they will get the edit permissions from the first group.

I would suggest double checking the permissions on the list and (as djeeg mentions in his answer) make sure you are not testing as the Site Collection Administrator as they have complete/full permissions to everywhere in the site collection regardless of what permissions you set the user in People and Groups.