At the beginning of the 2 beat bar, click F5, select number of beats per bar as 2, click Ok

On the next bar, click F5 and select 4 beats.

If you want a number of 2 beat bars, just click in the first non 2 beat bar. No need to worry about the style, it will adjust automatically


BIAB for Windows Version 2019 (643)
Windows 10 (1909)