You’ve changed the normal text style for the current document, but to apply this to every Google Docs document going forward, you need to open the Format menu again, then select Paragraph styles > ...

Day after day, you're greeted by the same blank page with that familiar Arial staring ... size and format of headings for a ...

and for headings, subtitles, and any other formats you want to save for future use. The default font is the one that appears when you create a new document: You’re going to be spending a lot of ...