Layout and content elements mixed together after update

Hello,
I tried to do a new page with different layouts and contents but when I update the page it’s mixing every layout and contents together. I did a third layout for example, but when I update the text are not displaying in the three boxes side by side, but one after the other, under my text. And different layout and contents are mixed up together, despite the fact they were separated when I created them.
I try at least three times and i tried to do another page but every time it is the same.
So please how I can fix this problem ?
I am losing my time trying again and again.
Thank you