Q: Scrolling became difficult

FWIW, if you mean you talked to LabArchive tech support and they told you LabArchive wasn't OSX 10.11.x compatible, it would be up to them to make it compatible. I doubt Apple would change their OS to make it compatible with LabArchives.

You may be able to revert to the OS X version prior to El Capitan, if it is in your purchases

list in the App Store, or if the computer shipped with a fairly recent OS X that you were

using prior to upgrade to the newest OS X version (El Capitan, OS X 10.11) and have a

Time Machine backup of that computer from when it was running the older OS X.

Usually you'd want to make an offline archive backup of your computer system before

venturing to experiment with a newer OS X system, so you can revert or run the old

system from a clone or an externally enclosed hard drive, or viable large partition...

• Make an appointment at an Apple Retail Store Genius Bar
• Find an Apple Authorized Service Provider

http://www.apple.com/contact/

There may be some other older software conflict causing the symptom you note. Did you

restart the computer in OS X Recovery and run OS X Utilities> Disk Utility> to check or

use the Apple Diagnostics to see if there is a hardware problem? You may need to see if

an Apple Store genius could help; you'd need to have an appointment. And backups of

your computer ahead of any change (or service visit, etc) is well advised.

• Startup key combinations for Mac -- Apple Support

• Mac keyboard shortcuts -- Apple Support

• Use Time Machine to back up or restore your Mac - Apple Support

Not sure what else to suggest.

Good luck & happy computing!