I do not understand the difference between root key and scale. Can anyone elaborate? Thanks
Maintain Current Scale
Keep selected scale while browsing. Allows you to browse chord sets in your preferred scale.
Scaler will keep the scale you chose to maintain instead of selecting the most likely scale in the list when navigating.
Maintain Current Tonic
Keep tonic while browsing.
Allows you to browse chord sets in your preferred root key. This is a good option for browsing artist and genre based chord sets whilst retaining the character and unique properties of the chord set.
Maintaining the current Scale will allow you to browse through while locking each chord within a given chord set to your chosen scale, regardless of whether the chord set is in minor or major.
Keeping the tonic instead will allow you to browse through and lock a given chord set to the root you have chosen while still leaving the chord set to play in it’s original mode. This will help retain the feel and character of the chord set.
For example if you have chosen Cmaj as your desired scale to work in and select Maintain Current Scale, each chord set you browse through will lock to Cmaj, adapting each chord in the chord set to the Cmaj scale. Though if you select Maintain Tonic instead, each chord set will lock to the C but will play whatever mode the chord set was originally in, maintaining the same scale degrees and relationships of the original chord set but just transposing to the C.