paper size is not user defined while printing

Just a month i have migrated from windows to Ubuntu 20.04 and it has libreoffice
In microsoft office i used to define page format with width and height and margins. When i take print it comes exactly the same what is defined.
but in libreoffice i have defined page width and height and margins
and while printing it prints differently not what is defined.

i am simply wasting papers.

Please help me how to print the paper size as defined

You must use the Page Styles in the LibreOffice. Because the .doc file format can not handle the Page Styles freature, the conversion (when you open a MS Office file in the LO) will lose some formatting properties.

Note: there is not (never was and never will be) 100% compatibility between the different file types.

Check the Print preview before you physically print a document. (or Export the document into PDF file format, and check it.

But in any case, reformat the pages by osage of the Page Styles before printing the document.