I probably need to improve my English, because I have a feeling that you misunderstood my question.
You are writing "I am the only user" and "there is just 1 user and it's me" and "role which is showing 'owner' ", but you are not confirming that your username is "admin".
O.k., let's try a different approach to the question that needs to be answered:
When you log in to Plesk, is the username you type into the "Username" field "admin" or is it anything else?
If it is anything else from "admin", you cannot access the Tools & Settings section. You must login as "admin". Are you using that username to login?