How to build application architecture correctly?

Question

Software design

I learned the basics of the language, but very few places teach the correct architecture of applications. For example, there is a GUI program. The program has many buttons. By pressing one of them, you need to create files of a given format, write to the log, save information in the database.
You can do all this in the callBack function on a button signal.
You can put each operation in a function and call it in turn from the callBack function.
You can create a class for each action (DBWriter, LogWriter, etc.) and call
class instances.
Or you can create a ButtonProcessor class that will contain methods for all tasks and call its instance when the button is pressed.

How to do it right? How to learn good scalable and testable application architecture?

Answer 1

I learned the basics of the language, but very few places teach the correct architecture of applications.

You need to teach a person to become an experienced specialist. Any ideas how to actually do this?
Gaining experience is a long process. It takes a lifetime, so someone will not teach you all your life.
For certain architectural solutions, patterns were invented, you can read books. But the correct application will appear only with experience. Write a lot, rewrite, read articles, look at someone else's code and other people's solutions. Any one source (book, course, example) will not be enough. Just develop curiosity.

Answer 2

DDD

Answer 3

Any architecture will be correct if it allows you to quickly create the application you need.