unfortunately yes…. it’s a WordPress thing, so whenever you activate any theme, parent or child, WordPress sees it as a “new” theme activation. It does not inherit or import theme option settings from a previous theme activation.
So if the child theme is not an option for you at this time, then you will want to try the Edit CSS plugin option, or if you use Jetpack, it has it’s own Edit CSS function. The important factor here is that any changes you make to the actual theme itself, you will lose those whenever there is an update to the theme and you would have to redo them again. Which is why if you use a child theme, or a CSS edit type plugin (or any other type of plugin), you won’t lose your modifications.