There are simple steps to change your logo. You can upload logo using the Theme Appearance Customize. In this tutorial. I will explain to you, how to add the logo in Rambo Theme.
1. Adding an Image Logo
Go to => WP-Menu => Appearance => Customize => Site Identity
Here you can add image logo of your website. You can upload .jpg and .png file. Refer attach the screen shot.
2. Adding a Text Logo
Go to => WP-Menu => Appearance => Customize => Site Identity
Here you can change the text for the logo. Refer attach the screen shot.
