The icon that opens preferences and settings has disappeared and I don’t have access to dimension settings and other settings. Please help.
What version of SketchUp are you actually using? Your profile says you have a Classic license SketchUp 2025 but there is no such thing. Are you using the desktop version of SketchUp or the web-based version?
Show a screenshot of what you are seeing. Dimension Settings are not in Preferences. They are in Model Info>Units which is found in the Window menu in the desktop version.
Please correct your forum profile.