I have versions setup for my project. I assign a fix version for each issue in the sprint. Supposedly according to JIRA's instructions to "Release a version":
1. On the Versions screen, hover over the relevant version to display the cog icon, then select Release from the drop-down menu.
I see:
This release contains XX unresolved issues .
Unresolved issues*Move unresolved issues to
I select where I want to move unresolved issues to as it suggests.
I click "release", yet it also moved all the issues that are done.