Adobe has released a new patch update 23.6 recently and it has introduced a major problem. Now it's impossible to change the font for items once you edit their text in the edit tab. We're working hard on an update to the plugin that would address this new problem.
In the meantime you can use below workaround.
If you would like to keep latest version of After Effects here is our little tutorial how to change fonts.
The workaround is not nessesary when you're changing the font right after adding the text precomp item (before changing the text). The problem only occurs when you change the default text before changing the font.