You can find how to reopen closed records form question manager in are help article here: 

https://inphase.zendesk.com/hc/en-us/articles/10148307666076

Hi Paul, I have an answer from the team.

Re-opening records can be done by an administrator in the ‘Instance Admin’ section in Question Manager. This is not covered by the NICE Video, but is covered in the Question Manager training video. This is only 1 record at a time though.

It can be done in bulk using a csv export/amend/import process, which administrators have access to, but we currently don't have training available to show you how to do it on your side. It is quick but a complex process to ensure nothing is "broken" on the re-import.

If you need all records moving back to ‘Open’ using the bulk edit, in this instance it would be best to raise a support ticket, I can do this for you from this question in the community area.

If you'd like me to raise the ticket let me know.

Thanks!