4x3 and 16x9 unresolved problem

[LesWant]

I supervise a hybrid service of worship in a church.  All the hosts and co-hosts work on a 16x9 screen.  There is a large screen in the church which is also 16x9.  Twice it has happened that instead of displaying things filling the 16x9 screen there has been a balack border all the way around with a much smaller 16x9 image in the centre.  When that happens the writing on the screen shared Powerpoint (which contains the words of hymns) is too small to read from the back of the church.  The Powerpoint is shared by a co-host who is working on a Zoom connection.

I know how it happens - If you start with a 16x9 screen and display a 4x3 image you get a black stripe each side.  If you then display a 16x9 image within this 4x3 screen you get black stripes top and bottom, leaving you with a small 16x9 image displayed on a large 16x9 screen.  I can't work out WHY it happens.  I cannot find any difference in the way we run the meeting on the two occasions that it happened.   You can see the effect yourself on YouTube, if you do a search for "Uniting Church Sketty" the services on 26th December and 14th November are affected, all the others are OK.

I came across this discussion - https://devforum.zoom.us/t/host-screen-format-changes-on-its-own/37253 which could be related - there seems to be things a random member of the meeting might do which affects the whole meeting.  I can't quite make it the same problem, but it could be similar.

[RN]

Hey @LesWant, as suggested in the Dev Forum thread you found did you attempt to uncheck HD if checked, and try checking and unchecking the 'original ratio' checkbox to see if that helps? May see a drop in resolution.

With HD checked, checking and unchecking the original ratio won't change your ratio due to the resolution of 720p and 1080p resolutions.