What program do I need to change audacity?

I know audacity is written in c++, but I don’t know what IDE do I should use to edit it.
Maybe Eclipse?

Extrapolating from “Eclipse” that you are on Windows, try reading Developing On Windows - Audacity Wiki .


I’m on Linux.

Then please try following the link “Developing on Linux” at the top of the page I already pointed you to.

Linux users are normally expected to compile widgets and Audacity at the command-line, so there are no instructions for visual IDE’s. See https://forum.audacityteam.org/t/no-targets-specified-and-no-makefile-found-on-make/26269/14 .