Updating Logged QSOs to Reflect the "my QTH" from which they were made
Backup your log: on the Configuration window, select the Log tab, and click the Backup Folder panel's Backup button
Filter the Log Page Display to contain only the QSOs whose my QTH ID items you wish to set. The Advanced Sorts, Filters, and Modifiers window's UTC panel makes it easy to filter the Log Page Display by specifying a starting date and time, and an ending date and time. More complex situations may require using an SQL filter to consider items like each QSO's Station Callsign item when filtering the Log Page Display
On the Main window's my QTHs tab
Use the Find myQTH ID panel's selector to choose the my QTH ID you want placed in the my QTH ID item of each QSO in the Log Page Display
in the Update QSOs in Log Page Display panel, click the Set myQTH ID button