(Menu Bar > Edit > Other Task Attributes > Offset Dates)

You can also display this dialog by selecting one or more tasks, then right-clicking, and from the context menu selecting Other Task Attributes > Offset Dates.

This page is used to shift (offset) the Start Date, Due Date, and/or Completion Date forwards or backwards by some factor of time. This can be useful if requirements change and specific tasks need to be started or finished sooner or perhaps later.