Missed the 30 minute edit limit. For those who are interested, here is a link to a list of true 16:9 resolutions.
https://pacoup.com/2011/06/12/list-of-true-169-resolutions/ and the true resolutions are in green.
Unfortunately 1600:900 is not a true 16:9 resolution but usable. Only resolutions that can be divided by 8 without modulus are "true".
Windows 7 also has infinite scaling instead of the preset 125%, 150% ...., so I reduced my resolution to 1536 x 864 and scaled the text to 110%. It is OK.
Thanks to everyone for all your help and direction.