Hello,
First of all thanks for choosing our Theme, we are glad to be you in WoodMart WordPress family :)
If you want to change the logo, the logo can be changed from the WoodMart > Header Builder > Your default header>> Logo element.
Or If you want to change the logo for mobile screens, you need to switch the layout to mobile and then edit the logo element to upload your custom logo.
Check this screenshot: https://jmp.sh/Cquv7lE
For updating your header you need to make sure that you are editing your correct(default) header. To recognize your default header you can follow the below documentation:
https://xtemos.com/docs/woodmart/header-builder/set-default-header-website/
Best Regards.