In Step 3 Customize:
On the left-hand side of the page, you will see our Text options, make sure that you select Text.
You will want to click and drag your cursor mouse in the correct text box, until it is highlighted in blue.
Quick Tip: you can Double-click to highlight one word, or Triple-Click to highlight the whole line:
Once you highlight your text, select your choice of text options: Font Size, Style, Color, Alignment, Bold, Italics, and Underline
If you have multiple Text boxes, you will need to highlight and make changes in each text box. If you cannot grab each box from their layer, go to the right side Layers and select your Text Box: