There is a built-in duration format, but Elapsed days is not an option. I want to display "2 days, 3 hours"
Try the following:
=split(days(B2,A2) & " Day," & Timevalue(B2) - timevalue(A2),",")
Days allows you to work out the difference between two days,
timevalue gives you the duration between two times as you have to extract it from your cells. I would then use
split to put the duration a separate column as formats can only be applied to a single cell as far as I'm aware
you could also just use
=Days and subtract the end date from the start to get the hours, but it won't prase it into days.