How to change audio input device (mic)?

I’m using Jitsi Meet via the web (so ‘https://meet.jit.si/<meeting ID>’) and the first time I used it on one PC I incorrectly selected the wrong audio input device (mic; I actually want to use the one built in to the webcam) and, without thinking sufficiently, clicked the link to always use that device. After joining a meeting, the mic icon at the bottom of the screen has the selection ‘down-arrow’ greyed out. Similarly, in Settings, there is no way to change the audio input device. Is there any way to tell Jitsi to reshow me the list of all possible devices on startup so that I can select the correct device? (I’m using variously Debian 10 and Bodhi Linux [based on Ubuntu] and I’ve attempted to install the Jitsi Meet client but when I run it it just sits there flashing the Jitsi logo drop shadow at me.)

Welcome to the community.

That selection is saved in your browser cache. Try testing in incognito mode and see if there’s a difference.

Thanks for your prompt reply. I tried logging in as a different user (root, in this case), starting up X-windows, running Firefox and accessing Jitsi Meet and, sure enough, I see the choice of devices. Can you tell me, please, where is the devices selection saved in the browser cache. My directory hierarchy below my home directory looks like:
.cache/
  mozilla/
    firefox/
      jeck6955.default/
        adb
        cache2/
          doomed
          entries
        OfflineCache
        safebrowsing/
          google4
        settings/
          main/
            ms-language-packs
        startupCache
        thumbnails

You can try going through Settings/Preferences in your browser, look for the “Privacy & Security” or similar section and then look for a segment that says “Permissions” or so. From there, you can see the selections you’ve made for your camera, mic e.t.c…

I’ve found it! I was expecting to see “Block new requests asking to access your microphone” checked, and it wasn’t, but selecting ‘https://meet.jit.si’, clicking ‘Remove Web Site’, then clicking ‘Save Changes’ has solved the problem. Now, when I visit meet.jit.si in Firefox it asks me which microphone to use. Thank you so much!