Hello samfrombrussels,
Thank you for being part of the Apple Community!
If I understand correctly, you are unable to connect your JBL speaker via Bluetooth. I will certainly try to help with this.
The first thing you want to do is try to connect to another device via Bluetooth. If the computer is able to connect to other devices, this would indicate that the computer is operating as it should and the next step would be to contact the speaker manufacturer.
If the problem exists with other devices, then I would recommend creating a test user to determine if the issue is system wide. The steps for doing this, and how to solve a problem that is user account specific, can be found here:
How to test an issue in another user account on your Mac
Have a wonderful day!