I can't get skype to use my mic through presonus firestudio mobile

This looks like a duplicate of your first question. Is it?

Just getting one of these... hope mine doesn't do this... However I can offer some suggestions to check that you have obeyed the rules of proper connection of music equipment to avoid noise and damage that can occur. FIRST... ALL and I mean ALL interconnected equipment such as amps, mixers, players, and computers, etc. need to be powered from the SAME receptacle or power conditioning module, even if it means running power extension cord. AVOID static discharges to any connected part such as mics, computer, etc.. These can often freeze equipment even though you don't feel the spark. Without knowing your particular setup in detail myself nor most helping people will not be able to offer much more help.

1. Go to http://www.presonus.com/products/Detail.aspx?ProductId=43
2. Click downloads
3. Download the software for your OS
4. Open the downloaded software and follow on screen instructions

The following is OPTIONAL and can potentially DAMAGE or BREAK your device:

1. If you wish to update your firmware open the universal control software
2. click settings > check firmware
3. then follow on screen instructions

Make sure all background processor hogs such as Antivirus, Antimalware, Anti-spam, automatic defragers as well as internet accessing program are either removed or disabled on your computer. These processor hogs cause overuns and underruns causing data loss which appear as clicks caused by discontinuities in the data stream.

What latency do you have the Presonus set to? Too low of latency can cause this issue.

Turn OFF all resource hogs such as Anti-virus, Anti-pop-up, and other background programs. Disconnect all internet access such as wireless and Ethernet service programs. All these resource hogs and programs for instance that keep track of when to run scans just cause interrupts of the servicing of the high speed audio grabbers. Your machine should be BARE of all these hogs.

Check your latency settings and try something higher that what it is currently set to. 1024 samples is usually a good starting point for most newer PCs.

On the back panel, beneath the socket that the IEC mains cable plugs into, the legend says 110-240v A.C. so I believe that the unit is already dual-voltage enabled.  the spec sheet on the manufacturers website confirms it is factory configured to work with 90-230 volts. http://www.presonus.com/products/detail.aspx?productid=43
However if you are not prepared to risk trying it I would simply purchase a separate voltage converter capable of delivering 20watts output. In the UK these cost about £10 (AUD$20) and  would be a lot cheaper than wrecking your  kit

Assuming you are connecting a microphone to this, if the mic is a condenser mic, make sure you have Phantom power on the PreSOnus turned on. You have given us almost no info of your configuration of mics and other devices connected to this unit.

Likely you haven't got the levels set properly. Start with the trim controls (head end gain) Make sure you are not clipping there. Also verify you aren't overdriving your amps. Remember that the outs are line level, not mic level so the gain oof following equipment needs to be set for line level.
ALWAYS USE balanced audio line from this unit... either XLR or TRS type cables. ALWAYS power ALL interconnected equipment from teh same receptacle or source to avoid ground bounce damage to circuitry. You don't say what you are using to record with. Make sure it has balanced inputs. For instance, connecting cables from this to the audio input jack of a PC which is unbalanced would be a disaster in audio quality. There would be a problem of levels and the unbalanced thing... You haven't given us enough information of your hardware configuration to analyze the problem more than what I have said here.