No audio other than Dorico after installing audio interface

Installed a Native Instruments Komplete Audio 1 interface and driver. Works well when using Dorico but cannot access sound from any other source, either when Dorico loaded or not. Unplugging interface restores audio.
Want to have YouTube tutorials playing on one screen while working with Dorico in the other, hence the addition of the audio interface.
Wondering if anyone has faced the same problem? Thanks.

In Dorico under Edit > Device Setup, does Komplete turn up with an own dedicated driver or are you using the Generic Low Latency Driver?
If you are using the Generic Low Latency Driver, then open the Control Panel and make sure the “allow exclusive access” option is turned off.
If you use a driver from Native, try to find a similar setting in their control panel.

Thanks for your kind and prompt reply. Am using the NI driver but there is no similar setting in the control panel. Dorico tech support sends me to NI but NI support useless on this issue.

You could also try FlexASIO. It’s also a generic ASIO driver that works with virtually any audio device. And it works in shared mode by default. GitHub - dechamps/FlexASIO: A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME.