Min Quantity, Quantity Step and Default Quantity Issue

Hi there. I have face the problem when i key in the Min Quantity value in product page, the value same goes to the Quantity Step automatically… Even i remove it and save, it still keep back and the value same as Min Quantity…

And another issue is, the Default Quantity didn’t allow me to save my key in value, after i save it, the value gone…

Could you please look into it? i have try to deactivate other plugin to check which plugin cause it but it seems not the plugin problem…