Playback Audio problem

I have been using Musecore on a desktop PC and a laptop PC for about a year with no issues; Currently using Musecore3, (I think). The program has worked well until about two weeks ago. The playback sound has been reduced to barely audible; I have asked the help forum and someone suggested reinstalling the drivers; I did that to no avail; the PC speakers work fine otherwise..(for non-musecore programs); I even bought new external speakers.
I seems that the playback is not coming through the external speakers but only through the PC speajers which are minimal...becasue the volume control on the speakers has no effect at all; there is only the very weak audio;
I am aware of no major changes or alterations to the computer or the musecore program; (although there may have been a Windows update in that time period);
The local computer shop tells me the problem is in the musecore program; what can I do to get this fixed? I am basically shut down until I get audio back...any help is appreciated, Thanks!