I want Smart Logbook to include hours I’ve already logged elsewhere.
The easiest and fastest way to get your previous time included is to add one or more carry-forward entries to Smart Logbook.
iOS:
Open the Totals tab and tap + at the top right.
Android:
Tap the menu (⋮) at the top right of the flight list and select “Carry-forward totals”.
The carry-forward entry screen is similar to the flight editor, e.g. you can log hours and takeoffs / landings, but the route fields disappear. Any values you add via carry-forward entries will be included in your overall totals and on the first page when you print your logbook. Optionally, you can set the date and/or aircraft model for each carry-forward entry. The latter is often necessary to ensure that your previous time appears in the right column(s) when printing your logbook.
These YouTube tutorials will tell you everything you need to know about logging carry-forward entries: