A running total starts at the first record and ends at the current row. Lock the first reference and leave the last one relative, then fill down. The start stays fixed while the endpoint grows. A zero adds nothing; a negative adjustment reduces the cumulative total.
A moving average uses a different window. Both ends move, keeping the same number of observations rather than including everything since the start. Put the first three-record average beside the third record, so you don't silently average a shorter opening window. For year-to-date reporting, use date boundaries instead of row positions. SUMIFS can include dates from the start of the year through the current record even when a report contains several teams.