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for plugins.on chrome, case you're not sure where..
open the "Chrome" menu
and follow the path "Settings" >
Show advanced settings > Content Settings. Scroll to the plug-in you want to control and check there if one you installed is enabled.

the busy site a few on here use it, and it'll highlight a blue circle to show notifies. the site is genuine.
screenshot example
Screen Shot 2018-08-18 at 23.26.54.png