Hello,
I realize on several print that I have made that filament does not stick completely. Or some part is “unstick” from the piece. Sorry if it’s not the right term, I am a beginner.
Here are some example to explain my issue.
Thanks for your help.
Overhangs, probably need supports on that area, you can’t print in thin air.
Perhaps try printing with supports. I’ve had the same problem when printing things that are raised high from the printbed. You could also try printing in a different orientation.
Hope this helps 
If we could see the whole thing it might easier.
Indeed, I needed support. I didn’t know about those and how to set them in Cura.
I just made some research after your comment and that fixed everything.
Sorry, I didn’t show the all piece. I mostly wanted to show details