Change font and size in TG Image services

HI
Our volunteer who first created the website moved away and I have little background. Mostly I have found solutions to my needs by reading the various online resources, but I am using tg image services for the 6 blocks on the front page that link to the major areas, but the font does not look right. How can I change the size and font selection?
Thanks for any help I might receive.

The page I need help with: [log in to see the link]