To change which themes are available network wide:
1. Click on Themes > Installed Themes in the Network Admin dashboard area.
2. Select the themes you want to make available to all sites by either:
- Clicking on Network Enable below the theme name.
- Selecting all themes you want to enable, then select Network Enable from the Bulk Actions drop down menu and click Apply.
Once enabled, the themes will be made available for use by site admin users and be listed in Appearance > Themes in the Site Admin dashboard.