If you create a new wallet with the new version of Armory, it will now derive the chaincode from the root key. Thus it doesn't need to be backed up, and will automatically use 1.35c.
The backup window will show you as much information as you need to be backed up. Please do not discard the chaincode on any old backups! They are still required to restore old wallets! It's only if the wallet was created after 0.88.1 will you be able to make a 1.35c backup.
Thanks for this information. I thought I would be able to create a 1.35c backup of my existing wallet but now I understand this is impossible