Could you please try this step-by-step process to connect? Follow each step in order. If it doesn’t work anywhere along the way, tell me what step it failed at, and that will give an important clue towards understanding the issue.
Turn off Bluetooth on any devices in the area that you have previously connected the speaker to and “Unpair” or “Forget” the connection in each device’s Bluetooth settings. This is very important to make sure the speaker doesn’t automatically connect to one of them instead of to the computer.
On the computer, click the Start button, then select Devices and Printers.
In the Devices and Printers window, if you see your speaker there, click it and select Remove Device, then select Yes in the next window.
On the Soundcore speaker, press the Bluetooth symbol on the top of the speaker to enter pairing mode. There will be a rapidly flashing blue light.
In the Devices and Printers window, select Add a device.
An icon for your speaker should show up in the Add a Device window. Click it, then select Next.
The speaker should connect. Try playing music through it. If it doesn’t work, continue with step 8.
Right click the speaker icon on in the system tray at lower right.
Select Playback devices. The speaker should be on the list under Headphones or Speaker and possibly Headset. Right-click it and click Set as Default device.