Your description suggests you're using tabs inappropriately. You also need to learn how to use paragraph Styles, especially, as those lie at the heart of how Word works. See:
https://shaunakelly.com/word/styles/stylesms.html
https://www.word-tips.com/microsoft-word-styles/
http://www.addbalance.com/usersguide/styles.htm
Finally, because Word uses the active printer driver to optimise the page layout, there is always the potential for the layout to change somewhat when the same document is opened on a computer using a different printer driver - which is especially likely to be the case when a different printer and/or operating system version is in use.
Ultimately, if you need to control how a document's layout will be presented to anyone who sees it, save it as a PDF and distribute that.