You are starting with a 4/4 style, so that is the correct place to start.
In BIAB, you can take beats away from the time signature of the style, but you cannot add beats. So you can't make a 3/4 style play 4/4.
To play 6/4, this needs to be done across two bars, a 4/4 followed by a bar of 2/4.
It's definitely less than ideal, but as Matt explained, this is a limitation based on the original architecture that still exists today.

The "4" in the Esus chord is not really required, because with a suspended chord, the 3rd note of the chord is replaced with a perfect 4th, so the program just needs to show Esus.

I'm not sure why the chord sheet displays 4/4 for every bar. I tried it and it looks OK. I used Bar Settings (<F5>) to set the number of beats to 3 on the first bar and then set the second bar to 4 beats.

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There is a button to show a Print Summary on the bar settings dialog. Mine looks like this:
_______________________
**** Band-in-a-Box Report of Changes in the song at any bar ******
Song Title is: Untitled Song, no file name (song not saved yet)
Bar 1: TimeSig to 3/4.

Bar 2: TimeSig to 4/4.
_______________________
Yours is probably quite different.


Perhaps use Bar Settings > Reset All Bars, and try again.

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