You could go for the dirty approach of changing the qa-include/pages/ask.php
Alternatively, the right approach is creating a plugin with, most likely, a combination of layers and filter modules, based on your requirement.
Is this plugin can meet your requirment
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.