Why is there sometimes no settings button in the control bar?

By design, when no or only one configuration choice is available for a selection that can be done in the settings menu (audio/video quality, subtitle, etc), the respective menu won't be visible. If it applies to all selection menues in the settings panel, then the settings section is hidden as well.

With regards to Safari on macOS/iOS: If your content has multiple audio/video qualities available, but no gear-icon is shown anyway, you are probably using the Safari browser on macOS or iOS. When the Bitmovin Player is used with Safari (iOS / OSX), the stream is played through Safari Native Player by default. This one doesn’t allow any manual quality selection, therefore no audio/video quality selection will be shown. Please see this guide how you can configure the Player Web SDK to use HTML5 playback instead of the native environment by default.