Yes, you can configure the desktop and mobile settings individually by switching between the Desktop and Mobile tabs.
Once on the Mobile tab, simply click on Copy Mobile Settings to Desktop located on the left hand side menu.
You can enable or disable the app by clicking on the toggle located on the top right hand side of the screen.
Scroll down on the left hand side menu bar and click on Reset Desktop Settings to Default.
Yes, simply click on the App Settings button located at the bottom left and make sure that under Video, the Native Player option is selected.
Click on the App Settings button located at the bottom of the page, followed by Remove. Then, reproduce the steps shown below.
Click on the App Settings located at the bottom left, followed by Reinstall. Then, reproduce the steps shown below.