The answer is "it depends". What does it depend upon? The settings you have configured in your Single Source Layout recipe. I suspect you are looking for the Automatic Synchronizing. It may have been turned off.
Apologies, as my crystal ball appears to be non-functional and my psychic skills are sub-par. Thus I'm unable to divine what specific version of RoboHelp you are using as well as what your RoboFlavor is. (if RoboFlavor sounds intriguing, click here and investigate the Edition and Version bit)
Please read that and come back to report with more info and we will be happy to advise where and what to poke to try and get things working as you want!
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