Can not edit emails using text - only HTML

This just started happening today.
I can not edit emails sent from I.S normally (in normal text format). It only gives me the HTML option, which is no good for me since I do not understand HTML.

Also, a smaller issue that started happening about a month back- now when I click edit it asks “the editor may alter your source code” - this box never used to pop up - can I get rid of it? It is a pain having to click ok every time.