The logo image in Matrix Themes can be changed with drag&drop tools.
Add a module 'Columns' to your footer section with only one column
Inside the column, add a module 'Widget/HTML' with the following code:
<var> draggable-logo </var>
Click the button "apply the styles" of the style editor or just reload the page to see the column in header section where you can add your logo using the module 'Photo'. Instead of the Photo,
you can add a module "Text" with a title. Please don't forget to add a link to it of your homepage;)
In previous Matrix Themes, the logo image is edited directly in HTML.In this case you need to upload your own image with the name logo.png ( Design > Custom template > Files ).
Every new uploaded file will automatically overwrite the old one. It is suggested to use an image with maximum width of 400px.
02. Advanced style editor
You can setup the main colors of your website with the Advanced style editor available in admin mode
Please check the additional resources working with the advanced style editor.