Having made a fork (of the audio library), made a change, and sent a pull request, I'm was then unsure how to re-sync my form with Pauls audio library.

This branch is 1 commit ahead, 7 commits behind PaulStoffregen:master
Looking around for a resync with upstream button and not finding it. I did find some instructions about doing this from the command line So I did that in the GitHub command shell, and it seemed to work.

Today looking at my fork, Paul has been busy so mine is behind again. (I have made no changes meanwhile). Okay so I repeat the same instructions from the tutorial:
C:\Users\Chris\Documents\GitHub> cd Audio
C:\Users\Chris\Documents\GitHub\Audio [master]> git fetch upstream
remote: Counting objects: 39, done.
remote: Compressing objects: 100% (39/39), done.
remote: Total 39 (delta 23), reused 0 (delta 0)
Unpacking objects: 100% (39/39), done.
From https://github.com/PaulStoffregen/Audio
   041e5ef..d951eef  master     -> upstream/master
C:\Users\Chris\Documents\GitHub\Audio [master]> git checkout master
Already on 'master'
Your branch is up-to-date with 'origin/master'.
C:\Users\Chris\Documents\GitHub\Audio [master]> git merge upstream/master
Updating c8e3500..d951eef
 Audio.h            |   7 ++++
 input_adc.cpp      |  41 +++++++++---------
 input_adc.h        |  11 ++---
 input_i2s.cpp      |  91 ++++++++++++++++++----------------------
 input_i2s.h        |  11 ++---
 keywords.txt       |   3 +-
 output_dac.cpp     |  43 ++++++++++---------
 output_dac.h       |   4 +-
 output_i2s.cpp     | 120 ++++++++++++++++++++++++++++++--------------------
 output_i2s.h       |   4 +-
 output_pwm.cpp     |  41 +++++++++---------
 output_pwm.h       |  11 ++---
 utility/dma_chan.h |   4 ++
 13 files changed, 197 insertions(+), 194 deletions(-)
C:\Users\Chris\Documents\GitHub\Audio [master]>
And then (from the github GUI) re-sync my local changes with my repository on GitHub.

So now I should be all up to date. Except no: now GitHub says
This branch is 7 commits ahead, 8 commits behind PaulStoffregen:master
and suggests I make a Pull Request. Choosing instead Compare, all the changes listed are ones that Paul made so why should I send a pull request? Paul's master already has those changes, it is where they came from!

What am I missing? Yes I could just delete my fork and then re-fork but I would prefer to know what I am doing wrong.