Templat compatibilty

I am using a template that is supposedly only 2.9 compatible? Here is the problem.
#1 The header only appears on the page that is a “post” page.

When I change this to a static front page – the header does not appear. Does anyone have a solution?

I was told this was because it was only 2.9 compatible. I have 3.3.1 installed – and would have revert to 2.9

I would appreciate any assistance in resolving my problem.

thanks in advance!