Hi Rachel,
As @JAM mentions above, if your session has an attendance object, which is added by default, users will not receive credit unless they have be marked attended. In that case, even if a user does click enroll, they still won’t be able to get credit.
Currently the enrollments setting does not bulk clone and we do not have a way to bulk update enrollment settings. There is a related topic post for it here if you want to add your vote.