I can’t shoot without aiming in Fortnite on mobile.

When you first signed in on mobile, you were given the option to select your fire mode. If you selected the mode Combined ADS+Fire, you won't be able to shoot without aiming. To change that follow these steps:

1. Go to Menu (the gear at the bottom left).
2. Choose Settings.
3. Tap Touch and Motion settings.
4. Under Fire Modes change Combined ADS+Fire to Disabled.
5. Tap Apply.