What’s the best settings to clear up a voice from the background of a voice sample? as I have a sample but it’s very difficult to make out what is being said… The voice in the background is at a distance but I can only make a a couple of words.
Do you want to reduce the background voice, or make it louder?
If you want to reduce it, you could try a Noise Gate effect.
If you want to increase it, you could try a Compressor effect.
You will not be able to dig a background voice out of a sea of foreground noise - only Hollywood can do that, though professional audio forensic experts with specialist equipment may be able to get some of the way.
It’s only two voices and when the background one speaks it’s at a distance so making louder and clearer to actually hear everything said and whether it’s a guys or girls voice.
The Compressor effect can help to even out differences in volume, but don’t expect miracles 
http://manual.audacityteam.org/o/man/compressor.html
Okay I’ve tried to with and still having trouble telling if it’s a guy or girls voice in the background.
Is anyone willing to have a mess with the sample and see what they think?
I’ve attached the sample if anyone is willing to try?
It sounds like the recording is too poor quality to be able to recover the background audio. We receive quite a few requests like this, but as I wrote in the first reply: “You will not be able to dig a background voice out of a sea of foreground noise”. That type of work requires specialised equipment and expertise, and even then is probably not up to the standard of CSI and James Bond. We are not able to offer such a service, either paid or unpaid. To find a commercial service for such work, try searching Google for “audio forensics” or similar.
You can manually go through the recording, selecting the quiet parts and apply the “Normalize” effect (Audacity Manual). The default setting will amplify the selection up to -1 dB. To speed the task up a bit, use Ctrl+R to repeat the last effect.
As predicted, you still cannot hear clearly the background voices, though you can pick out a little more.
Note also that if this recording is required for legal or tribunal purposes, it may not be admissible when edited or processed, and in some countries covert recording may be an offence. We are not lawyers and cannot give legal advice, so if that is what you need you will need to contact a suitably qualified specialist.