There are several inaccuracies here:
- The Music app that replace iTunes on Mac is called Music, not Apple Music (Apple Music is a service that you pay for to stream audio, ruin your local library and makes iPods worthless as it does not allow syncing them)
- Music does have the ability to not sync (aka: "sync off")
- Music cannot sync music from one device to another device. (aka: "synced my ipod to my other devices") what may have happened is a CD was purchased and these devices have their Settings->iTunes & App Store, Automatic Downloads, Music enabled. You can disable this to prevent this in the future.
Music is basically iTunes with a different name. So it generally behaves the same as iTunes. Though the windows may be slightly different.
Enough history and overview, let's get to tips.
1. If you even suspect the iPod might be in automatic sync mode, you need to stop the sync in order to change it to manual mode.
Hold the
Option and
Command buttons as you connect the iPod to temporarily stop the sync until the next connection.
2. Put the iPod into manually manage mode to prevent any syncing in the future from messing up the songs. This will prevent it syncing from any library until you turn this option off.
Click on the iPod in the left column, then click on the
Sync Settings button near the top right.
Put a check mark next to
Manually manage music, movies and TV Shows
Click the
Apply button
Now you can click on the
Songs section of Music in the left column.
Drag a song and drop it onto the iPod in the left hand column to add music.
Click on the iPod, select a track and press the Delete key to remove it from the iPod, answer Delete in the popup window.
You can click a song, scroll down through a list of songs you want, hold the
Shift key and click the last song you want to select a bunch of songs at the same time. Click and hold any song in the selection, drag all of them and drop them onto the iPod to put whole albums into the iPod.
You can also click a song, hold the
Option key then skip to another non-contiguous song, click on it to select 2 songs separated by others that you don't want, repeat to get more. Click and hold any song in the selection, drag all of them and drop them onto the iPod to put whole albums into the iPod.
The multiple song selection works on the iPod as well as the Music Library.