Two settings, and one of them is always on. Change it in Profile, then Settings, then Difficulty.
Easy Mode is the default. You get a Scroll Pass: one hour of unblocked apps, once a week, no coins needed.
Hard Mode removes the pass. Coins are the only way to open a blocked app.
Which to pick. Start on Easy. The pass is a pressure valve, and the first week is when you're most likely to hit a moment where you genuinely need an app and resent Aura for it. Move to Hard once earning feels routine, usually a week or two in.
Switching is instant and you can go back and forth. Changing to Hard Mode doesn't restore a pass you've already used this week.