Purchase group in default setting not overwriting in shopping cart

Hello Experts,

I have a problem in SRM portal, while creating the shopping cart, users can default their settings like (Product cat, purchase group, etc...). in the purchase group field, by default there is one value (assume X) and changing it to (assume Y), then as soon as i change it to Y, system again showing the purchase group as X only.

Could any one please advise what needs to be done. points will be awarded.

Regards,

Santhosh Kumar G