Unwanted linefeeds, lose colors, and can't see hidden characters

I’m running eM Client 7.1.30794.0 under W10 … I DO use text formatting (bold, color, and different font sizes) … sometimes I just type all text into a new eM Client email message … sometimes I cut/paste from Word or Excel … I constantly have problems with eM Client inserting unwanted linefeeds (between lines and wrapping lines too short) … I also sometimes lose colors … I don’t know how to see “hidden” characters (like LFs) … how do I correct these problems and how do I see hidden characters?