R12 Receivables Memo lines and Default tax codes

Hi,

I have business requirement not to change automatically tax code even it has been defaulted on the memo line setup.

Business case:

- user selects memo lines with defaulted tax code (e.g. 25%)

- user changes the tax code to e.g. 0%

- user decides to enter more details in description on the memo line -> when saved the tax code is set back to 25%

What I want to achieve is that this is not done and that tax code is not set back to 0% rather it stays as is on 0%.

I have tried the setup on the tax part (on 11 that was on the system option). It all works as expected, but it is causing issues to the business once the memo line is changed.