Setting up a Rifle Basix ERV-3 trigger

[PHINPAD]

I have just purchased a Remington 700 and had a Rifle Basix ERV-3 trigger installed by the seller.

The pull weight has been set at it's lightest and I wish to set it a little heavier. On looking at the mechanism it appears that there are 3 screws to chose from.

Before I go and mess up all the settings, can anyone tell me what each one of the 3 affects?
Or even better send me a link to some instructions.

I have been on the Rifle Basix website and surprisingly they only give fitting instructions and do not mention changing pull weight.

Thanks in advance

Dave