You can enable the scroll bar to appear consistently in Acrobat or Acrobat Reader by performing the following steps:
Step 1: Adjust the scroll bar appearance in macOS settings
Step 1: Adjust the scroll bar appearance in macOS settings
- Choose the Apple menu > System Settings.
- Select Appearance in the side bar.
- Choose Show scroll bars > Always.
Step 2: Turn on the preference to always show scroll bar
- Select Acrobat > Preferences.
- From the Categories on the left, choose Page Display > Always show scroll bars.
Please refer this link: https://helpx.adobe.com/in/acrobat/using/scroll-framework-upgrade-macos.html