GL Assign for sales

Sir,

Can anyone guide me how to check the Account key, Account Reference &GL assign is right or wrong,  also guide me how to GL Assign for Sales account.

at present i am facing problem for wrongly GL posting at the time sales

for example

Material code 100507 – GL should be GL 300200 instead of GL 300600

Material code 100607 – GL should be GL 300100 instead of GL 300700

and it is not only 2 Material master other also so i would like to check in all material

kindly guide how to check with details & SAP T-Code