Sure----You know how you have the 6 buttons on the bottom. And as you push either the right most, or left most button, your 180 scrolls thru the various pages? One should be your "EMS" page. This page displays RPM, manifold pressure, oil Temp, oil pressure, EGT's, CHT's, fuel Press, fuel flow, AND fuel level. In the upper right hand corner of the screen, where you see the 2 vertical bars showing the 16 gallons, there should be a "number" showing "total fuel remaining". After filling up on gas, you push, I think its button 5, which automatically resets your 180 to the 42 gallons. (I assume your plane's total is 42 gallons.)
Now having said all this, maybe its something you've got to configure yourself. When I bought the plane from the builder, this was already all there. I "did not" get the users guide from the builder. Its something I discovered I could download. Its this:---Dynon Avionics FlightDEK-D180 Pilot's User Manual
This is maybe 50 pages long, but its invaluable. After reading it, everything you ever wanted to know or configure on your 180 will be answered.
If you like, I can run down to the airport, and take some pictures of my 180 showing this EMS page, and the fuel totalizer. But you'd have to send me your email, as I'm clueless on putting pictures here on VAF.