This is a common Excel annoyance, and you’re describing it well 
When you press arrow keys while the “Apply to” (formatting range) box is active, Excel changes the range instead of moving the cursor, which feels like everything gets messed up.
Below are the causes + exact fixes.
When you are in places like:
So the range keeps jumping or expanding unexpectedly.
This is the most important trick.
Arrow keys will move the cursor, not change the range
When you press arrow keys while the “Apply to” (formatting range) box is active, Excel changes the range instead of moving the cursor, which feels like everything gets messed up.
Below are the causes + exact fixes.
Why this happens
When you are in places like:
- Conditional Formatting → “Applies to”
- Name Manager
- Data Validation
- Chart data range
- Any dialog where a range selector is active
So the range keeps jumping or expanding unexpectedly.
BEST FIXES (use these habits)
1. Press F2 before using arrow keys
This is the most important trick.
- Click inside the Applies to box
- Press F2
- Now use arrow keys safely
Arrow keys will move the cursor, not change the range
