New Goal/Reset Grace Period for Changes
When resetting a goal, I appreciate that you now allow me to specify a slope instead of starting flat for a week. The original purpose of starting flat is to make sure I didn't lose with an overambitious setting. But today I reset with the wrong slope (one year longer than I wanted) and now I have to wait a week to truly start my goal and that slope will be steeper than I want. I think you can solve both problems by allowing a "grace period" on setting up a goal; e.g. within the first 24 hours (or 10 minutes) of creating a goal I can change any of its parameters and have it take immediate effect.

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3 boxes to check would be ideal. "continue at same rate" - this could be default. "start flat" and "set a new rate".