Invoice no before invoice date and due date

is it possible to bring the invoice no above the invoice date and due date in invoice that we print ?

No it is not, there isnt a specific line in the theme code that shows each label. the group is shown in the same order in all themes.

thank you

Actually, you can do that with a custom theme. But it would take quite a bit of coding to implement multiple loops through the fields variable array with serial if statements. If that was not obvious to you from examine the code of one of the themes, the approach is probably beyond your coding skill level and you will need to hire programmer locally to assist you. Such techniques are outside the scope of this forum.