How to fix bugs in an installed program?

how to fix bugs in an installed program?

Hi tata, welcome to the Zorin Forum.
I think we will need more details to help you. Can you please tell us which program and what bugs or error messages you are seeing.
If you can add a screenshot of the problem you are faced with, that will also assist us here to provide you with some advice.

In addition to what zabadabadoo wrote, you can go to Synaptic Package Manager and check if there are any recommended fixes (for broken packages) there. Alternatively, uninstalling and reinstalling a package from SPM may fix it.