How do I change the Requisitioning BU in Responsive Self Service Procurement?

Summary:

The Requisitioning BU is not editable in RSSP, whereas it is in SSP, how do we configure it so this can be changed in RSSP. Am I missing maybe a role or privilege or data access or scheduled process?

Content (please ensure you mask any confidential information):

We have users who change their Requisitioning BUs preferences in SSP to raise requisitions for different BUs. If we change the BU in SSP and go into SSP, it brings up an error.

Version (include the version you are using, if applicable):

24A

Code Snippet (add any code snippets that support your topic, if applicable):