Review the "Configuring cluster storage" doc. especially the Update section. The UI has changed and you can now edit the persistent storage. See the source issue for additional explanatory text that we could add to the doc

https://github.com/opendatahub-io/odh-dashboard/issues/1610

https://access.redhat.com/documentation/en-us/red_hat_openshift_data_science_self-managed/1.32/html/working_on_data_science_projects/working-on-data-science-projects_nb-server#updating-cluster-storage_nb-server