When Acrobat is initialized (or just now when a popup presents "new Acrobat" settings, for AI I believe), if the suggested settings are not accepted and the user goes in and selects a document display size, that size is fixed permanently for whenever a document is opened. This can't even be changed by going into general (global) Preferences in the software. This thus presents a problem that can only be resolved by deleting the preference setting key in the Registry and thus reinstall the master preferences. (Note that this happened to me today when an Adobe screen came up and asked me how I wanted the new/AI? Acrobat settings to be set and I chose 0.125 as display size, hoping I was setting 125%. All my documents would open tiny, and the Preference tab could not change this. All I could do was change the opening size preference document by document. This was not good. So, Adobe Support had to delete the Registry key and we started all over with the suggested settings.) Given this issue, a user should not be allowed to choose other than the suggested preference for display size.