InfoPath Dev

I'm new to Infopath forms. I've been given a task to update the existing Infopath form. My question is once the form is updated, will it be possible to open the previously submitted entries of this form?

You should be able to do this without any problems.  Once you publish the new form, when an older form is opened there should be a yellow box at the top asking if the user wants to update the form.

 Just be careful about deleting anything from your schema, that could cause a loss of data or prevent your old forms from working properly.

Sounds good. Thank you so much for your help!