Several things can happen when you change the inflation rate, the nominal return rate, or both in regular assets for an Alternative Profile. For a full explanation, see Comparing Lifetime Values in Profiles With Different Interest Rates.
Note that if you change the inflation rate in your Alternative Profile, this Alternative Profile will use "base plan dollars" for the purpose of this relative comparison.
However, if you run this Alternative Profile as a standalone report or apply this Alternative Profile to the Base Plan and run the new base plan, the plan's amounts such as discretionary spending will now be presented in its own dollars relative to its own inflation setting and thus will be a little different different from the Alternative Profile amounts you are seeing now.
If you do not change the inflation rate and only change the regular asset return rate, the amount shown as discretionary spending will not change when running a standalone report or a new Base Plan report after applying the changes to the Base Plan.