Getting sound out off a Facebook Video Group meeting??

I'm asking for my sister, who has an Acer (I think) Laptop that has been
upgraded from Win 8.0 to 8.1 to 10 and makes use of Facebook group
Video-chat thingee.

Previously, when she has Video chatted, she can see and hear others and
they can see her, but not hear her, so she has to type in her responses
so others can then read them.

I duckduckgo'd for her "Enabling microphone in Windows 10" which brought
up lots of responses. Looking at the first selection, "How to Enable /
Turn On Microphone in Windows 10", she gave those suggestions a bit of a
go, but failed to improve her situation ...... because she says her
sound does work, i.e. she can, apparently, say "stuff" and record that
"stuff" and play that "stuff" back .... it's just that the "stuff" does
not get out on to the Internet!

Does anyone here have any suggestions as to what she could try, please??
--
Daniel