Prius Nav Coordinate Change Please HELP

I have been trying to get this question answered for 4 years and everyone tells me they don't know the answer. When I first bought my 2008 Prius with NAV, the very first time I pressed the Navagation button, it asked me to choose a voice, I had the choice of male/female/computer generated, I choose Female, and the next choice was the GPS format Decimal/Min/Seconds etc. I chose the one that reads W80 14'.34. What I want to do is change my format from that too the decimal format 80.34567282 etc. Also, there was a calculator on my MFD the first day I drove my car and after I setup the NAV system with voice & Datum format, the calculator has been gone.

I know I'm not crazy because I used the Prius to add up the total of my receipts I had with me that day.

Any help here? Is there a hidden menu where i have to push and hold some buttons to get back up to that original setup screen or some other way of changing the original setup?

Thanks for any and all help.