The Browserspy website's Adobe Flash Information page showed the version of Flash installed on her system was 22.214.171.124.
Adobe's Flash Player webpage showed the latest version, 126.96.36.199, was installed. I hit the Alt and H keys to bring up the Firefox help menu, then chose About Firefox, which shows the version of Firefox. The version of Firefox on the system was 49.0.1 and beneath the version was the message "Firefox is up to date."
sndvol in a command prompt window to open the
Volume Mixer. You can also get to the Volume Mixer on a Windows 10
system by typng
sndvol in the
Cortana "Ask me anything window.
The Volume Mixer showed a low olume for Mozilla Firefox, so I increased the volume by dragging the slider bar for Mozilaa Firefox upwards.
I could see the green bar in the Mozilla Firefox section of the Voume Mixer moving up and down as the YouTube video played in Firefox, though I couldn't hear any sound.
I muted the volume in Firefox by clicking on the speaker icon in the Mozilla Firefox section of the Volume Mixer.
When I clicked on the speaker icon again in the Volume Mixer to unmute it, I could then hear sound from the YouTube video play through the speakers.