Lab power supply ,Is it possible turn some have 3A in 5A ,can someone advice me?What i should change inside?

A current mainly depends on:
-Transformer
-Rectifier
-Power Transistor

You can change the transistor, rectifier, input and output capacitance, adjust current regulation, current shunt, but if you have (and it is) a small transformer with thin wires - nothing can help you. It will be overheat and just will break down.

thanks for respond ,i will buy new one..

sell this one get some money for new one

yes i will