Hey ton70n,
When you have Apex open, are you able to right-click the speaker icon in your Windows taskbar and select Open Volume mixer? That would likely be the next thing to check if you've already verified your in-game audio settings haven't changed. It may also help to select Troubleshoot sound problems from that same menu to see if Windows is able to locate any particular issues.
If you have Xbox Game Bar or similar programs on your system, I'd check the sound settings there as well as those can adjust volume for specific programs as well in some cases. You could also try a clean boot of your system from that point just to help make sure another program or process isn't conflicting.
Beyond that it may be worth checking your audio drivers and updating them if needed, or even reinstalling those particular drivers to see if that helps out. There are some steps walking you through that process in Step 9 of this Windows article, as well as some additional troubleshooting steps.