I usually use Tiny MCE but this is done using FCK. However according to FCK, the word "this" in the previous sentence should be large and in red. It isn't on my Firefox browser. However the other stuff below, and the bold FCK seems to be fine.
I would have thought this would be browser dependant, so maybe this link will help if FCK doesn't work either?
The other alternative is to paste HTML written elsewhere into the text editor, there is an option at the bottom of the text editor that says "Select only if all text paragraphs are enclosed in valid HTML tags." Never tried it but I expect it works... unless it's a victim of the recent "upgrade", ha ha!