Detailed Steps to Change Name/Logo in Cassiopeia:
  • Change Site Title/Text: Go to System -> Site Template Styles -> Cassiopeia - Default -> Advanced tab. Replace "CASSIOPEIA" in the Title field.
  • Replace Logo Image: In the same Advanced tab, use the "Logo" option to select or upload a new image, which replaces the text or default logo.
  • Hide Title/Logo: Under the Advanced tab, you can set "Brand" to "No" if you want to remove the default branding completely.
  • Use Child Template (Recommended): To make permanent, safe changes that won't be overwritten by updates, create a child template of Cassiopeia, as described in Joomla! Documentation. 
Adding Custom CSS:
  • To further customize the appearance, create a user.css file in the template's CSS folder.