Why are tracks moving different amounts with tempo change?

My first post here on the forum, though I’ve been using Cubase since v. 8. Forgive me if I’m using it wrong.

I didn’t set the tempo when I first imported and recorded the tracks, and now when I try and change it, they go out of sync with each other. I’ve toggled and changed everything I could think of (tempo track, change tempo in sample editor, musical mode) but nothing makes a difference. My vocal track (yellow) suddenly comes in too early, compared to the piano (blue).

This is due to tracksˋ timebase settings.

How do I fix it? Is there a way to get them on the same timebase?

The toggle for timebase can be found in the track controls.
On looking closer, it looks like you it could also be possible, you didn´t set the correct origin tempo tempo for the different files. Not so easy to tell, from only looking at the pictures. So the tempi of both tracks change, when you change the tempo on the transport bar?

The tempo of the tracks does not actually change, just their relation to one another—that is, coming in at different times. The samples shift in relation to one another not in speed.

So then it is quite certain track time base. Imagine a clip starting at bar 1 in 120 bpm will slao start at bar 1 in 130 bpm. but now if the tempo of the clips is not changed with the tempo, a clip starting at bar 5 in 120 will still start a t bar 5 in 130 bpm, but since the tempo is now faster, bar 5 is now earlier in time.
So if the tracks are in musical timebase, all clips will stick to their bar (musical) positions, but shift in relation to the absolute time positions.
If the tracks are in linear timebase, the clips will stick at their absolute time positions, but shift from their bar (musical) position.
So if you want to keep the clips to their Position in absolute time (which is probably what you want, when you don´t have the clips in musical mode) you have to switch the tracks they are on to linear timebase before changing the tempo.

Thanks, makes sense now. I’m now bouncing the clips to all start at the beginning so they’ll stick together. (https://www.steinberg.net/forums/viewtopic.php?t=136486) Thank you for your help!