Hello dear developer's i using JDSeattle
but i have 4 qwestions for you

Hi,

Replies in order.

1. To increase width of the columns in the top bar, please see this layout manager tutorial docs.joomdev.com/article/layout-manager-for-dummies/
2. This is not possible unless you manually change the code.
3. You are probably using boxed layout, where everything is saying between a certain width, switching layouts would help: docs.joomdev.com/article/astroid-layout-settings/
4. This is hardcoded in CSS and you can use Dev tools in your browser to inspect and fix.

Thanks,
Chetan

I didn't really understand
can you please more detail
what and how and where to do it?

The documentation above has videos and all the details you need.