Procurement Smart Forms / Mapping Rules to Default Charge Account

I am new to Cloud and we have a need for a specific smart form (which is project / task related and has been created and currently in use) that will override user settings (user's default charge account, preferences) and default to a specific GL account string at requisition creation. Can this be accomplished in standard setups using Manage Smart Forms, Manage Mapping Rules or other setup tasks?

Any input would be much appreciated.