If you saw your house on Trulia and you want to adjust the price, you should be in contact with your listing agent.. As Lori said, only your listing agent has the authority to change anything on your listing. All these other websites (Trulia included) pull from the local MLS and update their information on a periodic basis. Some update more frequently than others, some taking as much as a month to update. We are now a technology driven society and everything is on the web these days, so it's important that your agent has a good marketing strategy that includes feeds to as many websites as possible.
Thank you and have a wonderful day!!