Windows 10 Mail and Cox

Windows 10 Mail for Cox is giving me a headache.  I can receive OK but cannot send efficiently.  When I forward a message with multiple addressees  the text within the original message does not appear; recipients tell me that there is nothing included in the message.  And, in the text area it picks up the "subject" of previous received emails which cannot be erased.

 Sure wish they would design an EMail program similar to Outlook which worked well with Windows 7. 

The mail boxes are confusing:  Why are there  "Sent" and "Sent Messages".  Why is there a "send" at the composed area and one at the bottom of the page?

I have chatted online with numerous Cox agents and they tell me that my mail is configured properly; they have yet to tell me how to correct it or if there any plans in the future to do something about these problems.