Hi Venk
The setting for determination of baseline date is in the definition of payment term itself (check transaction OBB8). You can specify whether the baseline date should be posting date, document date, entry date or it should not be defaulted at all in the posting.
When you change the payment term, it doesn't always change the baseline date. For example, you have two different payment terms (A and B) and in both of them, the radio button 'entry date' is selected as default for baseline date. In the posting, when you change the payment term from A (default) to B, the baseline will not change. It is standard SAP process that baseline always gets determined / redetermined from the payment term. Moreover, the baseline date just gets 'defaulted' in the posting, depending on what you have set up in the payment term - it can be 'changed' manually by the user. Double click on the line item and change the Baseline date.
Thanks
Muthu