BT Email - Text size of composed message prints much larger than email header text

Mistral001

A few months ago the text in the body of a composed message increased in size to about five times its normal size.  When I print out any sent emails I, I get gigantic text in  body of the email with the header text remaining normal.  I have tried changing the text size setting from normal to small, but that still gives text about three times the size of the header and still looks very big when printed out. 

 I am using a Microsoft Edge browser.  My email from BT used to be called BT Yahoo Mail, but now there is no reference to Yahoo and it is just called BT Mail or BT Email.  I do not use MS Outlook.  When I do a test email to my own email address, the email still looks gigantic and prints out gigantic as well with the header of the email at normal size.   When I do a search of this on Google there a lot comes up but most is related to MS Outlook or is about the zoom settings and font size of the whole email.   I cannot find anything on my specific problem.  Any suggestions as how to fix this would be helpful.