Today’s Question: Once I’ve merged several catalogs into a single master catalog in Lightroom Classic, how to I make sure that Lightroom Classic will only use the new catalog, not one of the previous catalogs from before merging?
Tim’s Quick Answer: You can “lock in” a single master catalog by setting that catalog as the Default Catalog for Lightroom Classic in the Preferences dialog.
More Detail: I highly recommend using a single catalog to manage all photos in Lightroom Classic, rather than dividing photos up among two or more catalogs. I also strongly recommend setting Lightroom Classic to always open that master catalog by default, to avoid any confusion in the event you needed to open another catalog for testing, for example.
To set a default catalog, first open the Preferences dialog in Lightroom Classic. To bring up the Preferences dialog on Windows you can choose Edit > Preferences and on Macintosh you can choose Lightroom Classic > Preferences. Go to the General tab, and click the popup labeled “When starting up use this catalog” in the Default Catalog section of the General tab.
You’ll find the current catalog on that popup, along with any other recently opened catalogs. Choose the catalog that is your master catalog, and then close the Preferences dialog. From that point forward whenever you launch Lightroom Classic it will open the catalog you had specified, helping to ensure you don’t accidentally work with a different or backup catalog.