Hi,

If you need to make the customer menu only under Accounting for users. You can set the access rights for the menu items

Settings -> Technical -> User Interface -> Menu item

Search for customers

Here then you can see all the customers' menu item in each modules. You Can open the each records and add Administration Access rights for all menus except menu under accounting

Hope it helps

There's already a record rule for the access group  “Sales / User: Own Documents Only” that limits these users to their own sales invoice and credit notes:

[('move_id.move_type', 'in', ('out_invoice', 'out_refund')), '|', ('move_id.invoice_user_id', '=', user.id ), ('move_id.invoice_user_id', '=', False)]

You can make changes to this, as per my other answer. 

You can also limit access to menu items - either to the accounting users only or to a higher group for sales users. 

You will have to customize access rights:

- So the users cannot see the vendor bills menu

- And so that in the customer invoices menu, they only see invoices on which they are set as main "Salesperson". This will require changing "record rules i.e restrictions rules.

I would highly advise to get expert assistance from a developer or if you want, directly from Odoo.