At times I have quite a few formula kinds of objects in my documents (I teach Math) and I would like to change the properties of all of them at once, say: changing the font size and making borderless the frames all such formulas use. How can you achieve that?
I do this with macros. My library is contained in the document FormulaFontAndSizeToolsInside.odt. You can likely adapt the macros to your needs.
In addition to @Regina’s answer, formulas are contained in frames styled with Formula frame style by default. Modify this style for general formatting (borders, space around, wrap; etc.). This solves only the frame part of your question.
As an additional, there’s a LO extension for modifying the font and font size only:
https://extensions.libreoffice.org/en/extensions/show/formatting-of-all-math-formulas
Unfortunately, there remains this extremely significant limitation in Writer that it is not possible to control the appearance of equations in one place. If you chance your document from, say, a serif typeface to a Sansserif typeface, you are invited to click each and every equation, then spend some minutes in the “Fonts” dialog to change the fonts of Variables, Functions, Numbers, …, nine hundred times if the need be.
What Writer would need is a mechanism where equations could would their font settings from the document they are in.
Some extensions and macro’s are around to do this, but the success may depend on your LO version and perhaps your operating system.
The fundamental reason for this limitation (besides the fact that Math has not had significant updates for ages) is formulas are creates in a separate application. The returned object is totally alien to the styles machinery of Writer. And each object is also orphaned (not related to the others).
Many, if not most, users hope for an improvement in Math in this area. Any volunteers? I am personally not skilled enough.
Yes, math is quite limited in this area although it works quite generally. As person who writes both using LO writer and MS w* (depends on which co-authors i’m working with), i also encounter some problems on the later software. I hope there’s another & better concept for future LO math.