Dear nintex gurus, I have the following issue:

I wanted to modify a workflow, but I didn't want my modifications to overwrite the existing version, so when saving I unticked the relevant checkbox.

I thought that this checkbox will come back next time but it is not there anymore for that particular workflow. 

And now, when I tested and published, I want to have the possibility to overwrite the existing version with new one, but instead I have to save a new unpublished version, publish it, and delete the old one, which is not the best way.

So, the question is, how to get the checkbox back?