You've probably been sent here because you've been asked to locate your debug log, probably to send to the developers so they can (hopefully!) work out what's causing a problem that you're having.
The file name is quelea-debuglog.txt. Note that when sending the debug log, it's important to start Quelea, reproduce the problem that you're having, close Quelea and then locate and send the debug log - it gets refreshed each time you launch Quelea, so if you launch it, don't reproduce the problem then send us the log, we won't be able to tell much!
The location of the debug log depends on your OS, in general it is in the user home area inside a '.quelea' folder.
In Windows, it should be in this path:
In Ubuntu, it is located in:
Other distributions should be similar - the ".quelea" folder will always be in "~/.quelea", so it should be relatively easy to find this whatever version of *nix you're running.
It should be located in:
You can hit "cmd+shift+g" in finder (go to location), then paste this path in (replacing USERNAME with your username), and you should be able to see the debug log there.
Alternatively, open a terminal prompt and type: