Though you tagged common, I assume you mean Writer (which tag is writer.
You should have mentioned OS name, LO version and save format (because there are differences between platforms and releases and formatting stability is guaranteed only when saved .odt.)
What you experience is intended behaviour: Writer is flow-riented, not page-oriented. Pages are allocated on demand to cope with text size. So, if your document is page-oriented like catalogs, flyers, advertisement material, Writer is not the ideal tool. You should have a try with Scribus.
You can however “simulate” page independence by adding page breaks where you want to end a page: press Ctrl+Enter.
Note however that this does not protect you against page overflow where a new page will be automatically allocated.
From your question, I guess you’re discovering Writer and don’t know yet all its possibilities. Formatting and layout stability can be asserted with judicious use of styles. This is a fundamental notion in Writer to replace the manual usage equivalent to a mechanical typewriter where everything is explicitly typed. This does not take into account context (such as remaining space in a page) whereas styles can. I recommend the Writer Guide for an introduction to styles. Don’t expect to master the beast immediately. It requires many hours of practice, the voluntary drop of everything you think you know about document processing and a good mental model of the underlying principles.
