Hi, I am new to Audacity. I am trying to record a guitar, to my laptop using an interface. After a bar of music the signal fades to become inaudible. This It also occurs if I try using the laptops in-built microphone. I can’t seem to find any settings in Audacity to change this.
Any ideas please?
Thank you. Paul. 
I can’t seem to find any settings in Audacity to change this.
That’s because Audacity isn’t doing that. Audacity doesn’t apply effects, filters, or corrections during recording. Your computer or other software is doing that.
Auto Noise Reduction looks for sounds that stay relatively constant over a period of time. It naturally assumes that sound is noise and deletes it. Auto Noise Reduction can be OK for spoken word, but it just hates music.
Make sure Audacity is the only thing running on your machine when you do live recording. Shift+Shutdown Windows > Wait > Start. Don’t let anything else start.
Go into the Windows control panels and make sure there are no effects, enhancements, or corrections selected, either recording or playback.
This sounds silly, but I once got a new company computer from the Systems people and they left “Cathedral Effects” running in the sound by accident. For some reason, I couldn’t get the computer to pass sound tests.
Koz
Since you’re a New User, make sure your microphone or microphone system is plugged in and working before you start Audacity. Audacity checks for devices when it starts, or when you click Transport > Rescan.
It’s not the worst idea to make sure you’re recording from the right thing by gently scratching.
https://www.kozco.com/tech/audacity/clips/ScratchTest2.mp3
Koz