I am using the Aether logging software and it has two fields I do not understand: TX Exchange and RX Exchange. I know TX and RX refer to transmit and receive, but I'm not sure what to populate in these fields. There is already a frequency field so I don't know what goes in these and could not find an answer via a Google search.
It's intended for contest logging. Most contests require that you "exchange" some information. Sometimes it's as simple as an RST signal report and you'd just enter whatever signal report you gave an received, other contests require a serial number (you send "1" to your first contact and increment that by one each time, so that each contact gets a unique number) or a state, grid square, ARRL section, and in the case of field day, operator class (which is a code describing how many transceivers your "team" is using, and whether it's a club or just you, and whether you're in the field, in a vehicle, at home, or in an EOC). The contest scorers will expect your TX exchange to match your contact's RX exchange, and in some cases your score depends on what other stations send you (for example in contests where you get a bonus for each unique state).
If you're not using the logger for a contest, you would leave those fields blank.