I find the font too small on the forum when I look at it on my phone.... how can I increase the default size on posts body text?

Hi,

Do you want the default font size to be large for all devices or only for mobiles ?

This is a very easy process that you find the seetings option and follow the mention step,After following all the step if you face still the same, you can go to https://microsoftsupport.co/microsoft-support/ for help, here you can find all the help which you looking for.