Do you use capitalization in titles?

Do you use capitalization in titles?

This is a stylistic question. Or maybe about grammar... I don't know. When
and why do you use uppercase first letters?
I am German and in German documents, it is clear, to write all words like
always even when appearing in a title. The first letter of a title is
always capitalized.
In English, I understand, there are different rules. But are there
differences between UK- and US-English? Should that be localized to where
the thesis is written?
Until now, I have the feeling, that capitalizing main titles is done
everywhere (in English area)
This is a Book Title
In the US, chapter titles follow this rule
This is an US Chapter Title
but not in the UK
This is an UK chapter title



Are there any rules around? What is your experience?
Would there be a possibility to switch all the Table of
SomethingCapitalized to Table of something-not-capitalized?