Hi, I need help with the e-mail customers get for their booking confirmation, I need to change the logo but whenever I add or select new images in the "Images" category then it won't change in anyway.

"E-Mail Templates" category is greyed-out (although I'm the administrator/owner) so I don't really know how to sort it out

Please help me

Email templates are limited access because they involve a lot of mucking about with HTML.   RD disables this, and would rather do it for you.   You can ask to have it enabled if you have the skills in house.

The simplest thing is just to log a support call and send them the logo file.

Handy hint: the maximum width of the image file is 580 pixels.  Anything bigger and it starts to distort the email layout.