I am also very new to OnDemand solution but though to share some info related to account defaulting on requisitions. Hopefully it might be helpful for you.
In the default configuration, the default values of line item accounting fields on requisitions are derived from three sources.
These sources are:
- Accounting information associated with the requester through the User.csv file
- Accounting information mapped to the commodity code of the item through the ERPCommodityCodeMap.csv file
- Accounting information in the contract associated with the line item
The attached example shows the accounting fields for a line item on a requisition and identifies the CSV files that define the values that populate those fields.