How to Upgrade Using Miles on United? Upgrading a flight to a higher cabin class can make for a more comfortable journey. If you want to upgrade your seat but thinking about how to upgrade using miles on United Airlines. Well, to upgrade United flights using miles, one can visit the United Airlines website sign in to MileagePlus account, and make an upgrade, speak to a live person at customer service, or directly from the check-in counter at the airport. Read more: https://tinyurl.com/united-airlines-seat-upgrade #unitedairlinesseatupgrade #unitedseatupgrade