We can change the level of membership on a constituent record by following the steps below:
  1. From the Constituents Record, click the Memberships tab. 
  2. Click Other Tasks to the right of the Membership Program you will be adjusting the membership level on
  3. Click Edit Membership Details
  4. User-added image
  5. Expand the drop down menu next to Level and select the new Level 
  6. User-added image
  7. Click Save

Note: Keep in mind this does not cause a refund or an increase in the original price paid for the membership. If you need to charge the patron for an increase of membership level, you instead will want to renew or upgrade the membership.