On top of that, you are trying to add data to a field named cusid in the accounts table but there is no such field as your table was created.
Nor should there be. Links between customer and accounts should go one way. Doesn't matter which way, but only one way.
What I'm more than a little confused by: Why would customer and accounts be separate tables, in the first place???? As your tables are currently designed, each account can have many customers associated with it. Is that your intention???
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.