From the Project Summary screen, tap the Share icon at the top of the screen. You will see the Report Options list, where you can change photo and text size, as well as selecting a theme for your report. Once you're happy with your options, tap the tick at the top right to generate your report!
You can preview your report via the Overflow menu on the Projects Summary screen. Tap Preview Report and you'll see the Report Options list. If you tap the tick, you can see what changes you've made.