I plan to modify my Default Page Style, but I know (from the last tutorial) that if I don’t first open my Default Template I won’t be saving any of my work. And finally, you can start from scratch by right-clicking anywhere inside the Styles and Formatting window and selecting “New”. To do that, you select the Page Style you want to use as your starting point, then go the New Style from Selection button, which is the second from the right. Alternatively, you can create a new style based on the existing style, give it a new name, and add to your Page Styles collection. If you do that, you will change that style. You can edit either of them by right-clicking on it and selecting “Modify”. You will probably see two Page Styles already there in the out-of-the-box configuration, Default and Report. It is the second one from the left, the first one being the Cell Styles button.
With your Styles and Formatting window open and anchored to the side of your page, just go to the Page Styles button and click on it. One single sheet may take many physical pages to print, but it is all one sheet and it is all governed by a single Page Style.
And don’t be confused by the difference between a sheet in the file and a page when printed. In any given Template you can have different sheets with different Page Styles if you wish, but for any given sheet you can only have one Page Style. Page Styles in LibreOffice Calc set the properties for entire sheets of your workbook file.