Desktop scrollbar is too narrow

I have WhatsApp on my iPhone, but this question relates to the Windows desktop version.

I have shaky hands, so it's difficult to select the narrow scroll bar. Is there any way to increase the width to the standard value used by Chrome, Thunderbird, Word, Notepad, and so on?

I couldn't find any INI files, or anything similar.

I'm fairly comfortable in the registry, if necesary.

Thanks.