To display a log for your instance you should be able to set up a "basic" theme via your user menu >> themes page:
Once this is set-up, you can then enable the "widgetized" homepage via your admin console >> system >> settings >> home page link:
However, if you are seeing your logo point to a different URL after these changes are made I would recommend submitting a case in your customer group here in the Jive Community as a next step, so that a member of our support team can assist with further investigations specific to your instance.
Thanks so much for your prompt response! I will pass along your instructions to our internal community support team.