Unity provides standard spline asset,
use BGCurve only if Unity spline misses some feature
Personal Settings for each spline
There are settings, that allocated for each spline. These settings can be saved/loaded to/from disk. They include different colors, different settings for each field (like position, controls etc.), spline showing options etc. There are a lot of things you can customize. These settings are located under Fields and Settings tabs.
How to change and Save/Load Personal Settings
Settings are stored under 2 tabs- Fields (for positions and controls ) and Settings (spline related). After you make all the changes you can save settings either as default or some custom profile. Choose Settings tab and open 'Save/Load' foldout.
Shared Settings for all spline
There are also settings, that are shared by all splines. These include color of rectangular selection, on/off mode for menus etc.These settings are accessed by pressing Gear icon.