You should not change the settings in a member plan that has active members on it.
If you do, the members already on that plan do NOT get those new changes applied to them. A member's recurring information settings are written to their account at the moment of signing up so because of that, changes to a member plan after the fact will not affect them.
Instead to correct a member's billing situation, do the following:
* Create a new member plan with the correct billing terms (Edit Member Plan)
* Edit Member Details for each member
* Change them to the new (correct) plan
* Also set their "Renewal Date" to be the next time that they are to be billed on that new plan
* Press apply changes