Hello,
1. Login as admin or reseller, if admin click on Reseller Level
2. Click on Manage User Backups
3. Select all users or just the one you want
4. You must login with FTP (admin) and download created packages for each user in user_backups
5. When your new server is ready then you can upload all packages to user_backups folder via FTP
6. Login as admin or reseller, if admin click on Reseller Level on new server
7. Click on Manage User Backups
8. You will see all packages available on Restore > Step 3: Select File(s)
9. Check all and click restore.
This prosses is never undone so far I have done it
All users will be transfered with same username, password etc.
Hope this works for you