how do I decrease my margins

I want my margins smaller, making more room for text

See LibreOffice Help on Page.

In Calc, Format>Page, Page tab to access margins.

In Draw, Page>Properties

In Impress, for each different slide “type”, click on slide and Format>Properties, Slide tab

In Writer, this is a bit more complex because Writer is much more versatile. Display the style sidepane with F11 or Styles>Manage Styles. Click on the fourth icon in the toolbar (Page Styles) to list the page styles. I recommend you select Applied Styles from the bottom menu so that you see only those you’ve used.

Right-click on every style name and Modify. The margin dimensions are in the Page tab.

In case you use only one page style, you can simply access this style with Format>Page Style, then the Page tab “as usual”.

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