If you click on the Control and Plus Keys together on your keyboard (Command key on the Mac), you can enlarge the overall size of the screen. Text size will increase accordingly.
You can minimise the screen and text size by pressing the Control and Minus Keys together.
Regarding the Font size on Reports i.e. Date of Birth Report
You are able to download the report into a Format of your choice i.e. Word, enable editing, you are able to highlight the Font and enlarge before printing.