amount total is function/compute fields ,

As compute fields not store in db so you can modify it with the write.

you can override the function associated with the compute filed to modify it's value.  

  'amount_total': fields.function(_amount_all, string='Total', digits_compute=dp.get_precision('Account'),  multi='all'),

override  _amount_all  method .

Thank you, I understood more that amount_total is generated by _amount_all.

So, I tried to inherit as you said but I think I did something wrong.
Here is my code :

Hello,

I hope everyone is in good health. I am trying Odoo for test purposes.  I have created the sales order of about 6 items and I assigned them to the different team. My question is that is there any way that I can create the invoice for all 6 items separately from only one account? I have created two invoices of the sales order from two different accounts i.e. Administrator and demo account but for that I had to delete rest of the items in the list and after doing that I was unable to create any more invoice for that sales order from those account. I want to know if I can create separate invoice for all the items.