Your Banktivity file’s name ends in .bank8, and it normally resides somewhere in your home folder. By default, Banktivity suggests saving the data file in your Documents folder, though you may have chosen to store it elsewhere.

To search for the data file, open a window in the Finder and search for .bank8 (note the leading period) by typing that into the search field at the upper right of the window. Be sure to select ‘This Mac’ at the top of the Finder window. This should reveal any Banktivity documents on your hard drive. Checking the dates on any found files, you should be able to identify the current file. If you click once on it, the file’s path should show at the bottom of the Finder window.

Once you locate your file, simply double-click on it to open it.