I use Smart Sizer Gold by Amazing Designs Great Notions. Super-Super easy to learn and very affordable. I beleive Buzz Tools also has an affordable program to check out. ~Rita
i use wilcomtruesizer its free and easy to use,gr connie
Sew What Pro is a great program for resizing and editing, and reasonably easy to use. Depends what you want to do but it has worked well for me. You can download it for a free trial period and see if it works for you. And the back up support from Steve and Judy is second to none if you have a problem with anything they will help you out. (and no I'm not affiliated, just a happy customer)
I have been using Wilcom Trusizer and it is free. It took me a bit to figure it out because I am not good with the computer but I have it down pat now.
I use Trusizer too, and so far everything I've resized and saved in my format has sewn out beautifully! The best part is that it is free.