Global policies can be created from the Global Policies interfaces independently of API Proxies or from within the Development Tab of an API Proxy. A global policy can be used by zero or more API Proxies.
When an API Proxy is deleted, the global policies used by that API Proxy are not affected. However, any update to the global policy affects all API Proxies that use that policy.
Globalizing Local Politics
You can make the policy you create a global policy by clicking the Add The Policy As a Global Policy button in the upper right area of any policy you create while in the Development tab of API Proxy and entering a name in the Name field that opens.
Below is the image containing the settings for converting the policy to a global form over the locally set Basic Authentication policy: