How to edit objects used in templates?

I want to edit the sales invoice template. In that, i want to change the “qty” field to “weight” and “unit price” to “rate”. Can you guide me?
I tried understanding the template, and I see that the template is picking names for the column heads from an object “field.label”. If i can find the object to edit it, as I would have to edit it everywhere.

this is not a coding forum.
so if you are not familiar with coding please hire someone locally to design custom themes for you.

there is also a guide explaining how to change form titles. the same method can be used to change field labels.

you would have already got your answer if you had searched the forum for similar topics. the below topic explains your requirement.