All the above answers have DIFFERENT MENUs to me.

"Files -> setting -> Android SDK -> you can see the 'edit' that you can change the path of the Android SDK. -> click the download button"

No download button

"File > Setting > Appearance & Behavior > System Settings > Android SDK > [Edit] Button Click (Blue Color Link Button)"

No Android SDK button

"Open the Preferences window by clicking File > Settings (on Mac, Android Studio > Preferences). In the left panel, click Appearance & Behavior > System Settings > Updates. Be sure that Automatically check for updates is checked, then select a channel from the drop-down list (see figure)."

No drop down list