The offical refund policy

Is 85% for Standard passes (without plus upgrade) or 100% with plus upgrade
Promotional / discounted passes are usually not refundable with the plus upgrade they will refund 85%.

Currently Eurail offer the plus upgrade for free means that you get 100% refund.

Paperpass and Mobilepass have both the sameprice You can exchange your passes only via a refund a buy a new one.

I recommend to wait usually there are more discounts arround Christmas / New year, Valentins day or Easter no need to book a pass yet when you are not 100% sure.

Eurail tries to sell the mobile pass only but you can still buy the Interrailpass at many Ticket offices in Europe I bought them quite often just few days in advance at a ticket office next to me.

 

Hi Diana. Just to complement Seewulf's answer; please notice the Plus offer (which allows for higher refund percentages than the standard refund policy) is only available for electronic Passes - there is no such offer for the paper version of the Passes. It is possible to exchange a mobile Pass for a paper Pass, but this usually only happens in exceptional cases, as the paper Pass carries quite a few additional practical disadvantages and risks compared to the mobile Passes.

Cheers!