Maintenance for the week of December 22:
• [COMPLETE] NA megaservers for maintenance – December 22, 4:00AM EST (9:00 UTC) - 8:00AM EST (13:00 UTC)
• [COMPLETE] EU megaservers for maintenance – December 22, 4:00AM EST (9:00 UTC) - 8:00AM EST (13:00 UTC)
Go to your Collections by pressing U and you can select your current mount from there.
If you do not know how - you select "mounts" from the collections panel and then the mount category - hover with your mouse over the mount you want to use and press "E".