Back-dating transactions

Q.  How do you enter a payment for a previous day, for instance if it was missed or if it's an after-hours payment that should apply to the previous day's transactions?

When you enter the payment, e.g. in Reservation Transactions, check the "Details" checkbox near the upper right corner (or in later versions, use the "Show Dates" or "Show Details" checkbox).  This will add more columns to the transactions table -- in version 5.0 or later, the 2nd column is the Date, but in older versions it's the next one after Total.  Just click or double-click on that field in the grid and modify the date as needed.  Note that the ability to do this with previous transactions is restricted by an access level.