If this is the desk top short cut for Firefox Have you tried to just drag and drop it there ?

If this is from the start Menu and it does not pin, try creating a short cut by right clicking the Firefox Icon --> Create Short Cut then try to Pin the Short Cut. If pins you can delete the short cut you made in the Start Menu.

If still not working open File Explorer and go to C:\Program Files\Mozilla Firefox and find the Firefox.exe file and right click and Pin.

Please keep your Video Card Drivers Updated, very important. Thank You

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Thanks, I know of all of these techniques and they all work. Sorry, I need to clarify. You can pin it to the taskbar and move it to any position, but when you open more than one browser page, they won't join together in one spot. You drag them all over to the same taskbar location. Can this be fixed?

Right Click the Taskbar and then Lock The Taskbar

Some people have had the the issue I replied to.

Task Bar id the bar along the Bottom, Tasks is where they are Hidden just so on the right Place

If it is running programs besides the Hidden stuff can drag and drop them into Hidden.

This site is very useful : https://www.howtogeek.com/333110/how-to-customize-firefox-quantum-and-remove-the-white-space-around-the-title-bar/ Do a Search : Windows 10 then bookmark the list, have fun it is days worth of stuff. Can even turn back on Picture Viewer.

Please let us know if this solved your issue or if need further assistance.