Viewers in sharepoint 2010 site are able to edit the documents in a document library

I have a sharepoint site that contains 4 d开发者_如何学Goocument libraries. Even the viewers are able to edit the uploaded word document.I dont want this. Only the admins should be able to edit. How can i achieve this

You must have something wrong with the permissions on the library or the user is inheriting rights from somewhere.

I've set up a few doc libraries with some users having read-only permissions and it works fine.

Within the library use the Check Permissions button to verify what permissions the user has. The test will tell you whether their permissions have been granted directly or inherited etc.