All causes on GiveNow automatically have the CrowdRaiser approval feature turned off, so if someone sets up a CrowdRaiser it goes live immediately. To change this so that you review all CrowdRaisers before they go live, you'll need to tick "Approve new CrowdRaisers before going live".
This is done through:
Causes & Donations > Manage Causes > three dots / Edit > 1. General / Approve CrowdRaisers.