Estimated Tax Penalty isn't interest, so this wont help with that issue....but if you want to update the interest rates for late filing/payment purposes, you can do that here...you have to be IN a client file to get this Miscellaneous Option screen

I have seen other reports of the estimated tax penalty being computed wrong but that was was earlier in the season and I thought it was fixed, but you could be seeing returns that were filed prior to the fix....I guess its better for them to get a refund, than to get a bill.