CT332 Function of four buttons on top of control levers?

[BradWorks]

After the recent death of my father in law, I inherited responsibility for a John Deere CT332. I had used this machine a few times in the past for moving debris around using a CID root grapple bucket, but that was the extent of my knowledge about it. (This is the only skid steer I have ever operated.) Trying to learn more, I've downloaded the manual and read it completely, and watched lots of YouTube videos. However there's still something I'm not sure about - the two control levers (standard, not electrohydraulic) each have two buttons on the top of them. I know one of the buttons is the horn, but I don't know what the other three buttons do. The manual only provides information about the horn button. From my searching around, I suspect that the machine would have originally come with one button, and the other three would have been blanks (placeholders). And then someone might have added some functionality that is triggered by the buttons. But I was was hoping that someone here might know what buttons like this would do, or at least give me some suggestions to investigate. Attached are pictures of the two levers with buttons. Note that I know that the hydraulics are controlled on the right lever by tilting the lever in/out (e.g., closing/opening the root grapple bucket), so I don't think the buttons are related to that (although they might be). This machine only has two hydraulic hookups (male and female) so there aren't any additional hydraulic features that I know of. If it's helpful, there were two other attachments that he used with the CT332:

Harley Mx-7 Dual Cylinder Power Box Rake
CID X-Treme Skid Steer Brush Cutter Attachment

So maybe the buttons are used in conjunction with one of those attachments. If there is any other information that I could provide that would be helpful, please let me know.