I actually ran into this a couple months back when flying Horizon Air. I’d booked the cheapest seat but later realized I wanted more legroom for the long leg home. At first, I tried poking around online, but the options were kind of confusing. Ended up calling their support at 877-764-3622 and honestly, that was the fastest way to sort it out. The rep walked me through the upgrade choices, explained the price difference, and switched my seat in less than 10 minutes. I even asked about what would happen if I needed to cancel, and they said the same number works for cancellations and rebooking too. Super straightforward. So yes, you can upgrade after booking — just save yourself the headache and call.
