Change the batch size or efficiency in your equipment profile within a recipe, click save and it will ask you if you want to scale the recipe to match the new numbers. Also - if you change to another equipment profile it will ask if you want to scale to match it also! You can also use the scale button next to the equipment name.
Click the menu button in the lower right then Delete.
When you change a profile (equipment, mash, fermentation, water) from the profiles page, you have to reselect it in your recipe after you change it. This is because a profile in the recipe is not updated automatically to avoid breaking recipes unintentionally, it will stay at the same value as the profile had when the recipe was created. this goes for all profile types. New recipes will have the updated profile that you starred as default.
If your Final Gravity is set to a fixed number, you then have to click the Final Gravity button and then click Reset to get an estimated number. This happens if it is imported, or if the final gravity was set manually.