We are using SharePoint 2013, we have a library with contribute permission on it and when we try to share a document the default requested permission level in Access Requests list is edit how to change it to read?. Thanks in advance.
When you create a document library, it by default, inherits permissions from the parent site. This means all the groups continue to have the same access on the doc lib that they have on parent site. However, you can set unique permissions on a doc lib and set necessary access to selected groups.