Look into subevents in the manual to make a nested hierarchy of how you want to decide what gets the weird treatment. You'll need to compare if score > 1,000,000 change scoreText (or whatever you name your text/spritefont) to int(score/1000000) & "." & int((score-1000000)*.000001) & "million"
Something along those lines, but check the math because I didn't bother counting zeroes on my phone. Just have a series of checks about how big the score is or isn't and format your text with some math.