Learn FTP on FTP test if it’s not a higher one

My husband and I have both done the FTP (short) test a few times. When you don’t exceed your existing FTP at the end of the 20 minute test, Zwift doesn’t tell you your FTP result for that day. Is there a way to add this, so that regardless of the outcome (exceeds existing FTP or doesn’t), you can find out how you did on that test that day?

Check the box of your best 20 minutes at the end of the ride.(This Ride data) then subtract 5%.
So if it says 210, your ftp is 210 - 10 = 200.
You can also, lower your ftp number manually in the workout screen. At the end of your ride, the new higher number will be shown. Example, my ftp is 250 but I set it to 240. At the end of the ride my ‘new’ number may be 248 as long as I ride hard…