When you add / change / remove setings for engines / algorithms, you have to configure the UI in admin server so that can change the settings accordingly. The UI is configured by a json file dist/conf/init.json. This doc illustrates how to populate the change and have them show up in admin's UI.
Install PredictionIO from source
# Start admin server in the distribution directory.
cd dist/target/PredictionIO-<version>/
bin/start-admin.sh
# Edit init.json in the repository
vim ../../conf/init.json
# Copy it to the distribution directory. Unless you know what you are doing, don't edit conf/init.json directly in the distribution directory.
cp ../../conf/init.json conf/init.json
# Populate the change
bin/setup.sh
# After populating, you will see your change in Admin server.
setup.sh fails if the json file is malformed. You can use python's json package for error checking: python -m json.tool ../../conf/init.json.