is the possible to renew app.config when i modify application settings

hi

  i'd like to ask is the possible to renew app.config when i modify application settings in "propeties->settings.settings".

   i mean i'd like to let application settings decide app.config(that is to say, when i modified application settings, i hope app.config can be sychronized according to application settings)

   is it possible? and how?

  thank u very much for ur kindness help in advance

best regards

martin