The best thing to do is to go in to your Library2Go account and set the default loan periods for your account - 7, 14 or 21 days for ebooks and audiobooks. That way you just do it once and don't have to think about it again. We have instructions on how to do that on our Library2Go help pages here.
You can also adjust the loan periods for your account as you are checking out a book, but not for titles that you had on hold and are now checking out. Just below the Borrow button for a title, you will see a line of text that tells you how long you will have the book for. If you would like to change that, click on the Change link underneath.
Unfortunately, once the title is checked out to you, we are not able to adjust the loan period on that title.