Hi Færøerne,
Thanks for contacting us. We can certainly help provide information regarding the Fetch New Data setting on your iPod touch.
This setting lets you turn Push on or off for Microsoft Exchange, Yahoo! Mail, Gmail and any other “push” accounts you have configured on iPod touch. Push accounts automatically deliver new information to your iPod touch when new information appears on the server. To fetch or sync pushed data, your iPod must be connected to Wi-Fi and connected to the Internet. You might want to turn Push off to suspend delivery of email and other information, or to conserve battery life.
If you turn this option on, you should be able to set the interval to fetch data.
Let us know if you have other questions.
Take care!