If you don't want to play Valheim on the latest public version, and would rather play a different beta branch, here's how to change the version of your Valheim server.

Changing Steam Beta Version

Danger

Changing server versions may cause issues with your world save. As this deletes everything, download a backup to your PC first if you want to keep your save. We officially only support the main, public branch of the game.

1
Log in to Bropanel and Stop your server.
2
In the sidebar, go to Settings.
3
Edit Steam Beta Branch with the branch name you want to use (a list of branch names are below).
4
Click Reinstall in the top-right.
5
Select Format (keep settings), then confirm and wait for the install to finish.

Here are the currently available beta branches to choose from, they can be found here:

Valheim Beta Branches.

The latest version is public.