How to change jira System UI

[XXX_Yix]

Can I change the UI of the Problem Import screen?

Every time I import a problem, I need to select a fixed configuration file. I want to embed these files in the server so that I can select them in a checkboxlike way.

This should involve front-end development, I'm not quite sure how, does JIRA support developers to make changes to front-end code?

I wish someone would tell me how to do this.

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

Only if you are willing to code a new screen (and render yourself unsupported by Atlassian)

I'd strongly recommend doing this as a new app for Jira DC, rather than hacking the core code.