There are simple steps to change your logo. You can upload logo using the Theme Appearance Customize. In this tutorial. I’ll explain you, how to add logo in Health Center Theme.
1. Adding an Image Logo
Go to => WP-Menu => Appearance => Customize => Site Identity
Here you can add Image Logo according to your size. Firstly, Select image and crop image if you want otherwise choose Skip Cropping then Save & Publish
2. Adding Text Logo
Go to => WP-Menu => Appearance => Customize => Site Identity
Here you can change your text logo but firstly remove the image logo. Refer attach screen shot.
3. Adding Site Icon / Favicon
Go to => WP-Menu => Appearance => Customize => Site Identity
Here you can change your site icon. Site Icon means that your browser tab icon. Refer attach screen shot.