I just know that the GA filters can't apply to historical data, so does it mean the filter would only apply to the date while it enabled? For example, I added an IP address filter at 15th Aug, then removed it at 16th Aug. Then the report will always filter that IP address's data at 15 Aug, even after I removed the filter, is it working like that??
Thanks!!
Yes, that is how it will work. It's a good idea to always have a separate master profile that remains unfiltered, in case you do something like this and need the data from that filtered period.