To change your shirt size for your crate, simply log into your user account on Lootcrate.com and click on the My Account tab. From there, click "Manage Account."
Once you've clicked on "Manage Account," you will see your subscriptions, both active and inactive. Find the active subscription that you would like to change the shirt size on. From there, you will want to click the gear symbol on the "Looter Info" tab.
Click the "edit" dropdown.
The edit dropdown will then bring up the ability to change your shirt size for your crates.
Update your size, click "update," and you'll be all set! Happy Looting!