a few tips i can think of.
the snow/rain shield along with polarized sun glasses makes them harder to view, so remove the shield. be carefull what you use to wipe it off. maybe add a lap top screen protector to yours to keep scratches at bay. look for anti glare versions when shopping for one and trim it to fit. a razor should make better edges on your cuts.
use black for a back ground color. makes it show as high contrast.
use narrow beam.
shouldn't need any IR so shut that off.
turn the ping rate up to 4 for faster movement of the fish. keep it slow (1) for ice fishing.
try ice mode or if you have updated your firmware, try the new mode 1 or 2, which ever ice mode is now. mine is a lx9 with no new firmware, so i don't recall what the new ice mode number is now.
try updating your firmware today. it is free and supposed to be easy to do. you will need the right USB cable that fits the lx7. i believe it's called a USB mini (not micro) that has both charge and data capabilities.
not sure if the transducer came with mounting instructions, but if you transom mount it make sure it doesn't hang below the bottom of the transom, but try to keep it the same height.