I cannot see "Notes" when I open an Account profile

I cannot see "Notes" when I open an Account profile

I make a lot of notes for each of my accounts.

When I go to Accounts page and click a particular Account,  the Account opens and:
*  sometimes I see my notes, and the opportunity to add more notes
*  sometimes I don't.

How can I get access to Notes 100%  of the time that I open an Account?