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Changing the permission of browser notifications

In Firefox
Click the little circled (i) between the back button and the green lock.
Under Permission, click the X next to it to make it forget that.
When you reload Steemit's page, it will ask you again about permissions.

In Google Chrome / Chromium
Click on the green lock, find Notifications, and change its state to the preferred one.

If using chrome, click on the little "Secure" part that sits just to the right before the address bar in the browser.

In Microsoft's Edge or Internet Explorer, close the browser and load the page in decent Browser. :)