Brands logo in footer coming via CSS. You need to contact your theme developer to ask if he can quickly change those logos.
if not then you need to write custom css to replace the images.
regarding the black space this. this is because the logos are matched with the link url. if you’ll change the url then css code will not adobt the changes and you’ll not the see the logo.
you’ll have to write new css for new url or you ask your developer to make the desired changes.
Thanks