What is the simple subject in these sentences? I have a quick question. This is really confusing me.

Pls be understood a bit more.

The second sentence, --international and American championship titles--

international title --one title American championship--another title

so both create --titles, two of subjects connected with --And.

So, you need a plural verb---were.

However, what I understand from your question that is you need many morphological matters to understand verb+subject topics.

Pls you should check it out a morphology of grammar book, I mean you need a book that analyses many grammatical matters or you needn't only a plain grammar book.