For the love of god, someone please help me! Why is this so difficult to set up.
I’ve been trying for THREE days to get my bass guitar to make some volume on Audaicty.

I am using a Bandlab Link Digitial Duo Audio Interface- that is connected to a brand new laptop with Windows 10.

My headphones are connected to the interface. My bass is connected to the interface. The interface is connected to the laptop.

My settings in PREFERENCES are currently (as I have tried every variation):

PLAYBACK: Speaker/Headphone Realtek Audio
RECORDING: Device- Microphone (2- Link Digital Duo)

I’ve tried all variations and tried a splitter- still no sound.

I thought Audacity was one of the easier one’s?

Audacity is relatively easy, but Audacity is not the problem. The problem is setting up your interface and Windows so that it does what you need.
As you have another topic on the same question, I shall close this topic to avoid confusion.