if you are a pro user, you are able to use aliases to change the name of websites however this means you will not be able to use the official source feature, rather create a rem with children of the links you used, and then use aliases in order to change the name of the website
before :
then click on add alias:
type what you want in the box :
when its done it will look like this :
if remnote were to make the website powerup editable then you would probably be able to create this for the official source feature of remnote