Often do X by accident when I want to Y. How to prevent?

and vice versa How can I prevent this? Any ideas on how to separate these actions?

Preferences > editing behavior > allow dual trim only if both items are selected

Now that you have a real answer above, Maybe you can consider doing Z to avoid X and have less A and B as side effects, considering C can be set in conjunction with E ? 😅 (that thread title, , excellent)