Well, I’m on the beginning journey myself (1 year in), and I’ve gone digital too.
I started off with paper, as per Justin’s suggestion, and have a few printed song sheets (in plastic so they’re stiff) in my guitar case (which I really, really need to memorize). But found that, as @Mustela wrote, this is not easily edited, nor searched.
Then I started using the Learning Log built into Justin website, and a separate to store my digital songs. I’m a bit of a less disciplined learner, and am not always at a big screen nor online so found I didn’t use the log, and extend the digital software for managing my songs to also keep notes.
I keep all music and most notes in Songbook Chordpro (LinkeSOFT SongBook Songs and Chords), that exists across all platforms (15$US license for each platform, eg iOS, Android, Windows, OS X). I’ve configured it to make a local copy of my files so it works even with no internet connection.
The software allows me to change the key on the fly too (but not for the PDF songs–though they’re searchable), and its It’ll also do play along variable speed Karaoke style (if you own the mp3 of the song).
it is simple to import songs in chordpro from websites, and I can import from Ultimate-Guitar.com too.
. .
The application stores songs using the “chordpro” format (an Opensource standard https://www.chordpro.org/ ) which also supports, PDFs, TABs, JPG, and plain text. Using this format means that I’m not hogtied to this software I’m using–I can use any software that follows that standard
Notes can go in there too – either embedded alongside the song, or separately as a text file (masquerading as a song)
It has the idea of “setlist” (eg “lesson 08”, “aspirational”, “Current”, etc), “tags” (#folk, #intermediate, #easy, etc) , utterly searchable, synchronized on my cloud site.
There’s also a ton of support, that I’ve not used, for pedal support, midi support, syncing everyone’s display in a room, supporting different instruments for the same song (eg Uke and Guitar)
If you don’t have the app (say, you’re at a friend’s house w/out your device), and you can get online, you’re online source files are readable by any text editor.
Hope you find a good solution that works for you,
Cheers,
Bruce