No problem.
It would be helpful if you could share, which version of FxSound you’re using (can be located in the Help section of FxSound’s Settings menu), which version of Windows you’re running, and which type of earbuds you’re using (or, trying to use).
I have a pair of Bose QuietComfort Earbuds, for example, and cannot even successfully connect them to my computer.
Next, one of our most knowledgeable and helpful forum regulars created this thread that addresses exactly the problem at hand, of a Bluetooth device not showing up; so I would recommend taking a look there and applying the suggested tricks.
Also, among the many bug and error reports we’ve had, the issue with FxSound and Bluetooth devices is indeed a well-known one that reappears regularly on the forum, and, frankly, often goes unsolved as well.
So, while I am well-aware that this is not a solution to your problem with FxSound, it still seems worth mentioning that, if your problem should ultimately remain unsolved, there are many alternatives to enhance your audio available online (and probably even many more that I haven’t heard of yet); therefore, if your goal is to increase the sound quality of YouTube videos, you could still try pivoting to one of those for your buds.