It is considered that you did not specify the time in seconds.
When performing time calculation, you need to specify the time in seconds. Enter "3600 seconds" when specifying 1 hour.
Calculation of 1 day is "60 (seconds) * 60 (minutes) * 24 (hours)".

For example, if you want to calculate the date that is 7 days before the Date field of which field code is "A", you set a formula as follows in the Calculated field.

A-(7*60*60*24)