How do I return the text style to the original settings?

Sometimes when I copy & past part of an article, et,c it changes some of the format settings for TB email. I've been unable to change text style back to the original setting of the email. What I pasted will have ended in a footnote in superscript and I can't change the text style back to no specific text style or any other text style. IIf i click on discontinue text styles (in Format menu) if I try to continue typing email message it'll still be in superscript. This has happened multiple times. I can skip to the next line, doesn't matter, superscript will still be the text style, not the original text style of the email. How do I return the text style to the original settings?