[Change current output of PSU]

Try this :       

[0-30V Stabilized Power Supply]

Those two potentiometers are for voltage and current control?
Yes , see photo .

What means that letter "P." ?
Is that tumbler main ON/OFF switch?
Yes , when switch is ON , P. lights .

Those green numbers show voltage value?
Yes .

What circuit have you used for those LED numbers?
http://www.ebay.com/itm/DC-0-99V-Mini-Digital-Voltmeter-Blue-3-Wire-0-36-LED-Display-Panel-Volt-Meter-/160914959288?pt=LH_DefaultDomain_0&hash=item2577476bb8

[0-30V Stabilized Power Supply]

Understand but look at this photo :

[0-30V Stabilized Power Supply]

Yes,the transformer must be changed with 24V ,3-4A .
Now , the maxim output is 18,6V , 1.85A .

[Switch mode power supply. Help!]

Post photos , details .

[0-30V Stabilized Power Supply]

My project is here :