start/finish dates in P6 v8.1

Hi

We have recently upgraded to Primavera 8.1 web version, its not been easy i had only just got used to P6 Enterprise. Anyway when i am creating projects or updating old ones and adding in relationships the start/finish dates are not moving unless i manually change them.

Can anyone please help im guessing its a setting i have but i cant find any info on this. I have the duration type set to fixed durations and units/time, i thought this might be the problem but it doesnt appear to be?

Thanks in advance