Piano Roll basic problem, shortcut?

Hi. I have a question about the piano roll. I use the Sonar x3 these days. Suddenly, the "automatic fit" of the notes stopped. I mean when I make a note on the piano roll, and when I drag it, it automatically goes to the place of a quarter note or eighth note, for example.
 
This also happened with the track joining, in the track view. Now I have to zoom to the end to be able to put the note / track at the beginning of the measure. I have to keep moving it and pressing the play button until I hear it's ringing at the right time, it does not fit any more by itself.
 
Is there a shortcut to reactivate this function? Maybe I unintentionally turned it off. I hope you have understood, I have not found the answer anywhere, and this is disturbing me a lot: /

Thank you so much, you have no idea how much you helped me. Last thing: what's the difference between move to / move by snap that you quoted?

Glad to be of help
smusic.org explained the difference between snap to and snap by in a good way.
All the best.
 

Zargg
Glad to be of help
smusic.org explained the difference between snap to and snap by in a good way.
All the best.
 

Aw, thanks Zargg!  I'm touched :)