A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
If you enter a time such as 5:30, Excel interprets it as 5 hours and 30 minutes, not as 5 minutes and 30 seconds.
You will have to enter 0:5:30 to make Excel interpret it as 5 minutes and 30 seconds.
You can use a custom format to display the time as cumulative time in the cell, but Excel will always display a time according to your system time format in the formula bar. The system time format is for clock time, so if you use AM/PM for clock time, you'll see it in the formula bar. If you don't like that, switch to 24 hour clock time in Windows.