And here's a CFI tip for you: you don't need to define (to MyFlightBook) every single aircraft that you fly in in order to make a log entry -- you can use "Anonymous ASEL" (or Anonymous ASES, or Anonymous Light Sport) as one of your aircraft. You probably have a limited number of aircraft that you train in and you might want to define those, but this feature comes in handy for when you're doing training or a flight review in an aircraft that you don't want to bother defining because it's probably a one-off.
If you want to be more detailed when using Anonymous aircraft, go into your profile on the website, into Properties and set under "Show these..." to show Aircraft Registration. Then when you create/edit a log entry in the app or on the website you can type in the N# of the aircraft you flew in.
One other tip for jumping between planes. If you're tracking Hobbs/tach time in different aircraft, MyFlightBook is kind of problematic in that it pre-fills in the Hobbs time for any new log entry (for any aircraft) with the last Hobbs time from whatever aircraft you flew last. A long time ago I asked him for help on this and here's the sorta-workaround he came up with: if you long-press on the Hobbs time field n the app it will fill in the last-seen Hobbs time value for that particular aircraft *IF* it has "seen" that aircraft recently. (I don't remember the exact criteria.) So, if it doesn't work for you, then go to the logbook in the app (the icon looks like a clock) and click on the last logbook entry for that aircraft so the app "sees" the Hobbs time, and *then* go back to the new-log-entry screen and do the long-press to fill it in. Of course, you could just do it manually about as fast.
It's a good product, and has lots of features, which aren't always obvious. BTW: for everyone that uses it and likes it, you should contribute some money to the guy.