FAQ: Why Am I Unable to Enter Numbers in the CPP Benefits Estimate?
If the pensionable earnings area is greyed out for you or your partner, you may have indicated in your initial onboarding questions that you had already started receiving CPP benefits.
If this is not the case, you can change this setting in your Profile section. There is a checkbox directly below the date of birth info (the checkbox only shows up if you are age 60+ this year).