3pi Running slow

Hello 3pi Polulu World

I’m a new nerd and just got my 3pi the other night and successfully downloaded my first example code line follower
It all went fantastic until I decided to go advanced and then downloaded 3pi linefollower-pid
After this my poor little 3pi went slow so I measured the voltage on all 4 batteries = 1.42 each
So I replaced the batteries but still running slow

I can tell you that I have made the line with a think texter as opposed to the black tape

The problem in my opinion is something to do with how I have downloaded the code or changed some parameter
I believe it may have something to do with fuses

Is anyone able to help me and just guide me through the fuses setup just incase I have inadvertently change the settings

thankyou in advance
Downunder

Hello.

If you put back the first program on (the one that was working well), does it work the same way as it originally did?

- Ben