Step 1: To open up the Global Settings, Click on the gear icon on the middle right of the web application.

Step 2: You will now see the Global Settings on the right part of your web application as shown below.

In that settings panel, you will see various options that you can edit for ALL of your pages. This includes font sizes of texts and puzzles, puzzle grid size, puzzle clues positioning, borders, solution settings and colors. 

Note that whatever change you make on global settings will affect all the pages. 

Feel free to explore the settings until you are satisfied with your design.