Changing Equipment Profiles

Backstory:
I'm doing 3-4 gallon yields from extract and partial mash recipes. I've been doing so w/too small a boil kettle, 5 gallon.  This has been causing me to add back water to meet the target when adding the wort to the fermenter.  And also, I've had a couple big boil overs.  This has been a bummer as frequently my SG is looking pretty good only to be diluted by the water.

To solve this I'm going to upgrade to a 7.5 gallon kettle.

Question: When I create the new equipment profile, do I just change the profile referenced on the recipes that are using the old one?  Do I have to do some type of scaling?  Or is some other method the best way to change the profile?

You might consider leaving the old profile in case, for some reason, you need to use your smaller kettle in the future. The best way would be to create a new equipment profile. Once you've done that, use the Scale Recipe tool and select your new profile from the Equipment dropdown.

Note: you can copy/paste your old profile, rename the copy and change parameters as needed to fit your new kettle.

Also keep in mind that recipes in Beersmith are independent archives. Meaning just because you modify a profile, ingredient etc. does not mean that change is made in in your old recipes. Those will stay just the way your created them. So if you end up just modifying your old equipment profile and not making a brand new one as BOB357 suggests (great suggestion too btw) then you will have to go back into all of your previous recipes and change equipment profiles.