How to change font size on the message text inbox...to make it smaller in samsung GT-B7722

Open any text message & use the volume buttons given on the left hand side of the phone to increase & decrease the size.

Hi,
From your message menu, select 'settings'. When you are in the message settings, you would see the option of 'font size'. Change it to 'small'. Mind you, changing the message font does not only change the size of your message inbox. It affects everything as far as your phone's messaging is all about. That is the inbox, outbox/sent messages and your drafted messages.

So, I hope that helped you?
Have a wonderful day.