Hi there, and apologies if this question betrays my lack of knowledge of Jira!
We run different software projects for customers. On one project I can see a 'set resolution' checkbox, which means I can properly do burndown charts based on our workflow, because some items can be 'done' by the engineering team, but not necessarily resolved.

On another project (started by someone else) I can't set that resolution separately, and therefore anything classed as done is automatically resolved:

I've been through loads of the documentation and community posts but can't find anything that quite fixes it.
I am loath to delete the workflow and start again, as we're mid-project and that might cause a whole different set of issues.
It's a classic Jira board, not nex-gen.
Help please!