How to best study/follow games

I'm greatly enjoying John Nunn's "Understanding Chess, Move by Move." He helps us understand, as the title suggests, every move in the game. Setting up my chess board, I can follow along without a problem.

It's when he discusses other moves that might have been made that it gets hard for me. I could use my chess board, but then can't remember where I left off in the actual game.

A second board for these digressions might work (though sometimes there's digression upon digression, just as in a real game), but what I'm looking for is an electronic device or application, one where I can move the pieces (like 17 ... Nf6) in accordance to the moves in the book. And then can move pieces per the author's discussion of alternate moves (18 Ra4 ... Be2, 19 etc) but at the end be able to return to the actual game by just clicking on the move (17 ... Nf6) where I left off.

Seems this must be a common situation, and am wondering how better players handle this.

Thanks.

Steve (a beginner player but in my seventh decade) 

Hey Steve, you should check out the Study portion of the lichess website. You can analyze games on there and go through unlimited variations. I find it very helpful when looking at games in book, so I can actually focus on studying the position rather than just trying to keep tabs on where I am in the game.

Yeah, just use online resources to keep track of the moves and position
Then you can look at it on the board

m869, thanks, I'll go to the Study section, as you suggest.

safecar, not sure what those "online resources" are. That's what I was asking, basically.

m869 -- The first two games in Nunn's book are in the lichess Study section! lichess.org/study/dyR0sNU1

It's EXACTLY what I'm looking for. I can click on any move and the chess board rearranges itself to that move.

But, sob, only two games.

You can just add the rest by yourself!

@Steve_k Am very impressed that you are beginning in your 7th decade. Am doing the same at my 3rd decade now.

If you have loved John Nunn''s book, Next you should plan to read Irving Chernev''s logical chess move by move.

I had a similar problem of reading variations (digressions). Until I got myself chessbase 14. I even have the annotated database for most books. I can share with you. The good thing about CB14 is that you will use it offline.

It is need and shows the main moves in bold and variation in normal font. Get it from torrents and I will share with you whatever you may need.