Adding new approvers to existing Merge Request

I am trying to add new staff members for an existing MR. Currently, the MR has 3 users listed as Peer Review approvers. Two of them are no longer at our company and the third is the originator of the MR and cannot approve it.

I went into the project settings and added some new team members, but they are not showing on the MR.

Is there something else I will need to do to allow them to approve?