The "Allow Existing Members to Subscribe to the Trial" option within each member plan is member plan specific. If you have the field marked NO within a particular member plan, this means that current (or previous) members who subscribe to that member plan will NOT receive/join that plan at the trial price/days, instead they immediately become part of the regular monthly plan you have set up.
If you have the field set to YES, then any members (current, expired, canceled) will be able to join that particular plan at the trial price, even if they were in another plan that did not allow members to subscribe to the trial.
The setting will apply to any renewal no matter the users previous status
The field is "Allow Existing Members to Subscribe to the Trial?" and allows you to choose either YES or NO
1. Under 'Master Settings' choose 'Edit Member Plans'
2. Choose the member plan from the drop down menu
3. In the 'Allow Existing Members to Subscribe to the Trial' choose 'yes' or 'no' from the drop down menu