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.

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Install POS Awesome. Core POs has few issues.

Thanks Muzzy, I’ll try it.