@cpsyctc There is a difference between customising the LO application (changing its UI and sometimes its behaviour) and adapting it to one’s needs. You handle the second case with template documents. These documents have “special” extensions ott (Writer), ots (Calc), otp (Impress), otg (Draw). They mainly contain styles, but they can also host initial contents to spare you the pain of typing repetitive “permanent-personal” data.
You start by creating an “ordinary” document with File>New>… where you customise the built-in styles and add your own. This document is made a template by saving it with File>Templates>Save as Template. It will be saved in a directory listed in Tools>Options, LibreOffice>Paths where you can add your preferred one so that the templates are not saved in obscure locations.
With File>Templates>Mange Templates, you can designate your default template. There is one for Writer, Draw, Calc and Impress.
If you don’t make your template the default one, create your document with File>New>Templates so that the new document is based on the template, inherits its style collection and remains associated to it (so that any update to the template is forwarded to the document next time you open it).
In your case, you want to highlight text. Is this a systematic highlight over all your text? In this case, customise Default Paragraph Style. Since it is the ancestor of all other styles, your modification will impact all others.
If you need to highlight only selected words, create a new character style you’ll name Highlight and set its Font Effects parameters. To highlight, apply this style on the selected word(s). To change the highlighting, modify the style and the modification is applied instantly to all occurrences. Of course, provided you have no conflicting direct formatting on the highlighted words.
