POS amount update not correct

Dear all,
I have ERPNext v13, when I change number items in POS, the total amount seem not update immediately but theGrand Total is correct. Then if I change to newer number items, it will show total amount of previous number. Can you show me how to fix it, many thanks for your help.

Install POS Awesome. Core POs has few issues.

Thanks Muzzy, I’ll try it.