Can't get music deleted from iPhone when syncing

Question

I had a computer crash and had to restore all music from backup drives, iPods and iPhone.
I built my iTunes library back and am ready to sync again with my iPods and iPhone.
There's no problem with the iPods.
All music that was on there is automaticly deleted and the iPod syncs perfectly with the new built library.
With the iPhone though it's not working.
On the iTunes screen I can see there's no music left.
But after syncing the music always seems to come back and can't get removed from the iPhone.
I sync the iPhone by selecting the playlists.
So on top it says 0 music gets syncronised when I haven't selected any playlist. On the bottom of the screen there's no music and the iPhone seems almost empty.
That's good, as I want the new library to be put on the iPhone.
But after syncing I can see there are no playlists on my iPhone anymore, which is correct, but the music itself stays on the iPhone.
I don't know what's happening.
Usually when I select some playlists or unselect others, this affects the syncing of the titles immediatley, putting songs from the selected playlists on the iPhone and deleting the other ones.
But now it's very strange.
The playlists are deleted or added the way I want them to be be, but the music itself stays on the iPhone, always giving me the notice that there's not enough space on the iPhone.
I just can't see what's happening. I've been doing this without any problem for such a long time.
But now it doesn't make sense to me.
Looking at the screen after not selecting any playlists, there shouldn't be any song synced to the iPhone.
That's what I also see on the bottom of the screen. But when clicking on syncronising, after a while it's full again, meaning no music is erased form the iPhone.
Can anybody help me with this?
Thanks.

Answer 1

I'm sorry, I tried but it didn't work well enough.
I have two screens and when I take screenshots, the picture of the iTunes screen is too little to make sense.
I'll try to explain what I'm doing now.
I only selected one playlist, containing 27 songs.
When I syncronize it says there's 52 GB free space, which is almost everything.
There's almost no audio. that's good as it's only about 27 songs here.
So far so good.
The thing I had to look for, 'On this phone' is not on top of the page, but on the left my iPhone appears as a device in the menu.
When clicking on it I can see Music, Films, TV shows and the one playlist I syncronized.
Films and TV shows are empty, in music only the 27 songs appear.
Still so far so good.
But then when I click on synchronising again all of a sudden it's filled with audio again for 52 GB.
There's almost no free space. However there's still only one playlist with 27 songs marked to syncronize and in Music  I can still only see the 27 songs.
After a while it jumps back again to 52 GB of free space with almost no music.
The thing is it looks good on the iTunes screen.
The iPhone appears to be almost empty and in Music I can only see the songs of one playlist.
On the iPhone itself though all the music is still there.
So there's no correllation ibetween what iTunes is showing, almost no music, and what my iPhone itself is showing.
I just can't get rid of the music that was still on my iPhone before I had a computer hard drive crash.
I want to get rid of the old stuff on my iPhone, so I can sync it again with the new music library I created.
Do you think it's possible that it's something to do with iCloud or things like that?
Is there no other way to empty my iPhone from all the music and afterwards sync it again, without losing all the other stuff?
I'm using iPods from the beginning, having a big music library of 40.000 songs.
I never had a problem like this, though I'm very used of suncing iPods with certain playlists, artists etc.