want to sign in easily to all apps using my account
want to sign in easily using my accounts
Question marked as
What happens when you do?
Do you get any error message?
See -> If you can't connect or sign in to iCloud
If you can't connect or sign in to iCloud - Apple Support
BTW:
You are sign in here . . . with your Apple ID & Password.
Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.
You can’t merge multiple Apple ID accounts.
What happens when you use the same Apple ID & Password that you use to sign in here?
See the following Apple articles
Sign in with your Apple ID -> Sign in with your Apple ID - Apple Support
Manage and use your Apple ID -> Manage and use your Apple ID – Apple Support (UK)