Unfortunately, hash (like passphrase and blocksize) is one of the settings that can’t be changed once a backup has been created.
If you try to run a backup in which the --blockhash has been changed from it’s original value, you’ll get something similar the message below.
Note that there is a tool that can let you do things like change the passphrase (by downloading, re-encrypting, re-uploading EVERY file) but I doubt they’ll be able to do a blockhash change.
