Adding numbers to questions

can i add question numbers to already existing questions 

We do not have an automatic way for you to add numbers to your questions on the form, but you can add the numbers manually. You can do that by editing the form in the Form Builder, and simply clicking on the field, and then clicking on the label/question of that field:

The label / question will become editable, and you can then add a desired number in front of it:

I hope this helps. Please let us know if you need further clarifications or assistance, and we'll do our best to help.