I have uploaded a logo to my header. But the logo appears very small on the website. I have png files in 500px, 1000px and 5000px, but that does not alter the size. Where can I adjust the size?
Default logo height is 60px, and that cannot be changed unless you edit the theme files (please read to know more: https://opendept.ticksy.com//ticket/1427509/). Width can be customised accordingly with your need.
In your case, I'd recommend to create a logo that is wider, but keep the height at 60px. So, let's say your logo is 120x60px, go to the Customizer and adjust that settings typing 120px (see screenshot: https://ticksy_attachments.s3.amazonaws.com/Screenshot%202019-12-21%20at%2020.35.44%20PM_880.png).
Hope that helped