Thanks for the suggestions. Unfortunately, they did not help. You must have a different version of software as there is no Softphone Settings > Call Control. I tried going to Settings, Call Settings, Call Using and changing the dropdown there but that did not help.
As far as the suggestion about choosing the devices from Hardware Settings, I cannot do that because all the devices there are grayed out. And in the Windows 10 sound settings, it already has the correct device set as the default. So there is nothing to be done there. I have tested this with nothing plugged into the laptop, so that only the internal speaker and microphone are present, as well as with an external headset with microphone plugged in. In both cases, all the devices in Hardware Settings in MiCollab are grayed out and do not work in MiCollab, though they work elsewhere in Windows.