How to enter a title, composer, lyricist, etc.

How do I enter a title, composer, lyricist, etc. so that it appears in full score and in parts? When I enter this text in Engrave mode to full score , it does not appear in parts. When I enter the same text in Score info, it will appear in pairs but not in full score. Please give me a simple advice how to do it. I do not need to know anything about the Master page, etc., because it’s unnecessarily complicated and I do not need it. I’m mostly arranging for bigband and for smaller jazz groups.

File menu > Project Info
Pull-downs let you set separate info for each flow or at the project level.
Tokens-- {@projectTitle@} etc. --let you insert or change the stored info in text frames of Engrave Mode.

Then, as pianolo says below, you need to edit Master Pages.

If you want it to appear automatically in each part layout, you DO need to know about editing master pages. Why do the same work ten times on ten part layouts when you can do it once on a master page?

This is the glory of “master” pages. If you go to engrave mode for the full score and then one of the parts, you can edit the master pages and add appropriate tokens. Once you’ve done this (and Dorico auto-populates some of them) you go to the project info, enter what you want into the appropriate fields and then that info will show up on each layout automatically. This way you edit the tokens once and get the same results across the board. What is dually excellent is if you decide to change part of the info, you can do that in one place (the project / flow info page) and then it will auto-update anywhere the corresponding token is used and therefore you won’t have to edit every single layout.

Is there a video on YouTube that I would understand?

Yes. Dorico channel, search for “master pages.”