Hi arjjay,
I'm not the best person to answer this, as I'm pants at techie questions of this kind. That said, I think the times are dictated by the location of the host servers. So, depending on who your broker is and where they're based - that will govern the chart times, and I suspect you can't change them. However, I could be wrong - but an e-mail or phone call to your broker will answer the question definitively one way or the other.
Tim.