I am using Gmail with too many labels with multiple levels. I also have the Preview Pane lab enabled.
I want to move the chat window to the right side. It was previously there. But I am not able to move it now. Please guide me to do the same.
I don't think it's compatible with the Preview Pane feature. Even if you have them both enabled, the Preview Pane has precedence and it moves the chat list to the left side.
You can disable the Preview Pane lab: Go to Mail settings -> Labs -> Search for Preview pane in the page -> Set it to Disable -> Click Save Changes at the bottom of the page.
To enable the right side chat window: go to Mail settings -> Labs -> Search for Right-side chat in the page -> Set it to Enable -> ClickSave Changes at the bottom of the page.