Bring a Bit of Color to Some Office 365 Apps
Those who notice these things (not me) pointed out that Office 365 now allows users to select three new themes for browser apps. The themes are called Rainbow (Figure 1), Ribbon (Figure 2), and Unicorn (Figure 3). To select one of the new themes, go to the Office 365 home page and select your preferred theme from the settings (cogwheel) menu.



Some Apps Like Themes, Others Don’t
Joking apart, some serious points can be made about Office 365 themes. First, they don’t apply everywhere. For example, the old OWA interface (the one most generally used today) ignores Office 365 themes while the new OWA picks them up. Apps like SharePoint Online, OneDrive for Business, Planner, and Yammer are also happy to use whatever theme you select. Even the Office 365 Admin Center uses themes, but the EAC or old SharePoint Admin Center won’t. Second, Teams is an Electron-based app (even when running in a browser) and always uses its own interface elements.
Controlling Office 365 Themes
Last, as pointed out by Brian Reid, you can stop users changing the Office 365 theme they see in the Organizational Profile. Go to the Office 365 Admin Center, select Settings and open the Organization Profile. Select Manage custom themes for your organization and set the slider for “Prevent users from overriding their theme” from Off (default) to On. Figure 4 shows the location of the slider.

As you can see, there are other tweaks you can make in the Organization Profile, like adding your organization’s logo. Go mad and be creative!
Being a serious kind of book, Office 365 for IT Pros doesn’t normally pay much attention to minor details like browser themes. But one of our team members likes this stuff and felt we should mention it. So we have. But that still doesn’t mean that we cover it in the Clients chapter. We have other stuff to discuss there, which is what we cover themes here…
Cant see these three newly added themes. My Organization Profile is set to Targeted Release for everyone.
This isn’t a support site. You should report the problem to Microsoft and have them check your tenant.