This feature can be enabled via menu item File → Auto-Reload (Auto-Reload after external modification).
By default, if file is updated (and it was changed before, or AutoReloadNonModified set to true), you will get a popup informing you about the update and request for reload.
There you have several choices:
In addition, there is a check box: Do Not Ask Again. If you will check it, you will be not asked any more, and your last choice will be used. If you select:
You can only reset settings later by reseting check from workspace file directly (no UI for this).