Force-refresh your web page. Force-refreshing a page will clear that page's cache, allowing you to see the most recent version of the page as opposed to any information your browser saved in the past: Windows — Press Ctrl+F5. If that doesn't work, hold down Ctrl and click the 'Refresh' icon. Mac — Press ⌘ Command+ ⇧ Shift+R. Twitter's Mac app has been updated to include a new 'Pin to top' toggle that allows you to see a live stream of tweets without refreshing. Twitter support announced the change overnight.
To quit (close) a Mac app normally, choose Quit from the app's menu in the menu bar, or press Command (⌘)-Q. If the app doesn't quit, follow these steps to force the app to quit.
How to force an app to quit
How To Refresh Your Mac
Press these three keys together: Option, Command, and Esc (Escape). Or choose Force Quit from the Apple menu in the upper-left corner of your screen. (This is similar to pressing Control-Alt-Delete on a PC.)
Then select the app in the Force Quit window and click Force Quit.
You can even force the Finder to quit, if it stops responding: Select Finder in the Force Quit window, then click Relaunch.
Learn more
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How to force an app to close on your iPhone, iPad, or iPod touch.