Architect theme - Replace header/banner image and github logo/button


As the title says, Architect header/banner has a blue graph like image as the background, and a ‘view project on github’ button.

I would like to replace these but not sure how if anyone can help please?

I went into /images and replaced header-bg and github-button with new images using the same file names. But nothing changed and stayed the same.

Much appreciated thank you.