I'm going to need a few more details to help, because I would not want to assume too much.
If you want to achieve something specific, just ask. Plenty of us do this a lot.
What are you trying to achieve ?
What control resources do you have ? Fader, knobs, mouse-only ?
How are your automation preferences set up ?
Here are mine ...
WRITE usually instantly starts writing all parameters that are both activated and armed when you hit play.
You can also start writing stuff when transport is stopped. That's the third dropdown from the bottom on the prefs page to control whether or not that happens.
If you want to write a static setting across a time selection, I recommend the Latch Preview mode. (see video link in my signature about that)