Iexpense Account Generator

Hello,

While creating Expense report in R12.2, the system is Defaulting accounting from Expense report template and/or employee expense account on Global HRMS. Currently we have 5 segments, Company, Natural Account, Cost Center, location and Activity. The first four segment can be driven from the template; however, the Activity segments is not always constant, it depends on transaction, is there any option to select this segment while creating expense report or is there a workflow that i can customize.
I have already customized project expense report, but I'm not sure if there is any workflow for non-project related expense reports.