Follow the instructions below on How to change the logo and favicon of my virtual store created in PrestaShop 1.7?
First of all, open your PrestaShop dashboard. On the left side choose the design section and then click on the theme & logo button.
Here we have to choose the header logo and favicon. First, add The logo. So Now Click on Browse Button.
and select logo and click on the open button.
In The Same way, we have to add a favicon. After that click on the Save button.
now let's see if your favicon and logo were added or not. Now you can see our logo and favicon have been added successfully.