Change font size of all post in Atahualp theme?

Did you know Atahaulpa had lots of support here, https://forum.bytesforall.com/

Also you can change the theme looks in the dashboard/atahaulpa theme options.

Thanks, I did not know that but it still does not solve my problem.

I want to increase the font size of all posts in the main body in one go! I dont want to do it individually?

seriously still need some help with this please guys?