How do I automatically change a assignee moving tickets

[Wim Oor]

If I move my issue to another project, I want that the assignee will changed automatically to a pre-defined assignee for that project. 

How do I do that?

[Nic Brough -Adaptavist-]

The move functionality doesn't support any field edits - it's purely to allow you to move an issue while keeping it valid for the new configuration it might be landing in.  It's a minimal amount of process to do one thing properly.

You'll have to find or write a new move process that can change arbitrary fields outside the context of "keeping it valid".  Or, you could find/write a listener that can listen for "issue moved" events, scan the moved issue and change the assignee after the event.