Figured out why i can’t get squared up

So was watching the usual daily 6 hours per day badminton coaching videos and came across a video that shows you should move your LEFT foot infront after your ready position jump instead of the RIGHT going back first to get squared up better for smash/clears

This is the reason why I cant never seem to square my shoulders rite MY coach always told me Im not squaring up rite but never told me move the left foot infront first instead of right foot back. ….just to show you how coaching in india is far way behind then other countries. ( I am currently going to the best academy in my city)

can someone who understands why explain this to me
And why its better then right foot back first ? Is this for clears , drops and smashes ? And all situations or is right foot back first better in other situations??

here the link its at 2:30 minutes