You can change the Member's plan with the following steps.
1) Go to the Members page.
2) Click on the Member's name that needs to have a different plan.
3) On the Member's profile, click "Edit Profile" on the upper right side corner of the page.
4) Go to the Change Plan section.
5) Click "Change Plan" link.
6) Choose a plan and options that you want to assign to this Member.
7) Enter the start date and end date. You can leave end date blank if it's not determined yet.
8) Enter additional one-time charge if necessary.
9) Click on "Change Plan" button.