If you're using Mozilla Firefox, press the button, click Add-ons and open the Plugins menu. Click the Adobe plugin from the list and select Always Activate from the drop-down menu.
In Google Chrome, you need to type chrome://plugins/ in the address bar and to press Enter. After that, click the Enable button below Adobe Flash Player:
If you're using Internet Explorer, press the Alt key and from the Tools menu select Manage Add-ons. Click the Toolbars and Extensions from the Add-on Types window and enable the Adobe plugin. If you can't see the plugin in the list select All add-ons from the drop-down Show list:
Opera users will need to select Developer tools from the Opera menu and to click the Plugins button. Select All and then enable the plugin. Check the official web page for further information.