The storage-init.sh script is used to initialize the Virtuoso storage. The following lines can be adapted to set the passwords of the HobbitPlatform and the dba user.

# Setup the HOBBIT Platform user
/opt/virtuoso-opensource/bin/isql 1111 dba dba exec="DB.DBA.USER_CREATE ('HobbitPlatform', 'Password'); GRANT SPARQL_UPDATE TO "HobbitPlatform";"

...

# Finally, change the 'dba' password
/opt/virtuoso-opensource/bin/isql 1111 dba dba exec="user_set_password ('dba', 'Password');"

Please note that the script can be executed only once with a newly created Virtuoso database because the last command changes the password of the dba user which is used to execute all the commands in the script.