Ive created a site with quite a few pages with all of them set as master, so they all update automatically if i change anything on the master page. I want to edit and change something on a specific page, so i right click on the specific page and select 'unlock all on page'. When i do this, nothing happens and the page is still locked. Is there another way round this? Thanks!
You have completely misused the very purpose of Master Pages.
They are meant to contain content and layout that is constant across site-wide pages - background, header, footer, menu, etc.
Locking pages - or items on a page - simply prevents content on that page from being changed.
Dani Beaumont, of Adobe Muse, has an excellent video on the subject of Master Pages