Your current is already a little lower than the stepper max (they look around 2.6A) so be careful adjusting at all. Too low will work but may cause missed steps.
Thankâs Justin, I will be very careful
With a bigger motor the temp will most likely drop compared to what you experience now. So I would not think any tweaking would be required at this point 
I have just connected the new motor, it had some different colours red green blue yellow, so I connected
red to red
green to green
blue to white (as it was with the other motor)
yellow to black
but it wonât work
How to determine which of the four wires that form pairs:
Do this with the old motor also, that way you know the pair pinout that you can use for the new one. If the motor turn the wrong way, simply swap one pair around.
All working now . you were right Angus the colours were not related at all, why canât they be standard.
Thank you all for your help