The link below will install a series of Groups to help you track the following:
Part 121 Total Time.
Part 121 Actual Instrument.
Part 121 Night.
Part 121 PIC
Part 121 SIC
Note: to mark a flight as "Operated under 121", simply use the checkbox labelled "Part 121", and LogTen will do the rest! If the "Part 121" checkbox is not visible, please visit this article to make it visible → Configuring your Logbook
Download the Group by clicking/tapping here.
This will open LogTen and install it automatically.