Invite-only Forum - Can non staff members invite others?

I have a similar question. Who gets to invite people to the forum?

My new site is invite only and we have a small community of novice users, all invited by myself and all given trust level 2 by default.

When my users want to invite more users I tell them to look for the invites page in their settings but they can’t see it. Presumably because of a setting or because of their novice status in the system.

Do I need to increase their trust level or make them moderators/admins?