You can bold by adding !! before and after the words.
Thanks Brendon. I should have mentioned that I am using the ipad app. That doesn't seem to work. Is there another method?
I've just checked and this formatting seems to work in our iOS app. Please try to delete and reinstall our app and try to add tasks with this content:
This !! text !! will be bold
This __text__ will be italic
The "text" part should be formatted once you save the task.