Since i have assigned an identity plate (PNG I uploaded) to the Backlight Standard Page Template and my Album Set Templates and Album Templates have Backlight Standard Page as their template the logo should show up on Album Set Pages and Albums right?
It all depends on the page template you've assigned to your album and album set templates.
Have you created a new page template that uses your logo? If so, make sure it's assigned to your album set and album template.
Also, if you want your logo to appear on client log-in pages, be sure you assign your page template in Client Response Settings under Personalisation.