That thermometer will only show you the ambient temp and the humidity.

Get another digital thermometer with a probe to test the warm side. If the ambient temp is around 80, that's probably the cold side temp too.
The probe thermometer will tell you the hot side temp. Make sure to put it under the substrate to get a more accurate reading.

I would set the flexwatt to 94F to get that ambient up a little. That'll put the hot side around 90-92F.