See below:

You should be protected in the upgraded class.

--- PROTECTION GUIDELINES-DOMESTIC UA/UAX -----------
- THIS POLICY APPLIES TO UNITED/UAX/UNITED.COM
BOOKINGS ONLY
- UNITED IS RESPONSIBLE TO PROTECT TICKETED CUSTOMERS IN
THE EVENT OF A SCHEDULE CHANGE IN THEIR TICKETED CABIN
- UPGRADED PSGRS AFFECTED BY A SCHEDULE CHANGE SHOULD
BE PROTECTED IN THE UPGRADED CLASS IF AVAILABLE.
- IF NF/NC IS NOT AVAILABLE - PROTECT CUSTOMER IN F/C
IF AVAILABLE AND CONTACT SD FOR CONVERSION.