You have to be in the step editor, once you pick the song and the chart. It will open the step chart. Then do this:
-Push "Esc"
-Go to "Step Statistics" or the first option depending on your theme, I guess.
-The first two options on that list should change the difficulty and foot rating respectively.
And to answer your second question, as far as foot ratings of 1-10 go, I compare mine to the Arcade charts, anything beyond this is really your call. The hardest I typically see are 13's, anything beyond 14 is pretty rare unless its a stupidly hard chart that's not meant to be passed. |