internet explorer-yahoo e-mail?

how do you change to font style in the compose line.? it somehow got change from arial to this bold lettering. the subject
line is fine. i have tried, tools, options and font change, also tried
general preferences and nothing seems to work. By Mary SHighlight text and go to top toolbar (above where you type messages) and change font. Do the same if you want to make something bold, italic or underlined as well as changing font colour. Make sure you highlight it first.