Try this
- Name the action, such as lowering the volume or leaving a light on, and its immediate effect.
- Keep the thanks attached to this occasion. If you want a repeatable preference understood, state it plainly in addition to thanking them.
A worked example
“I noticed you turned the music down when I started reading. That made the room easier for me to use.”
An invented example to adapt, not a real exchange or a script you have to follow.
Before you leave it here
Do not infer a motive you cannot know. If the action was coincidental, the useful information about your preference can still stand.