eason101 I am afraid that the interface scale setting was added in 3.0 so cannot be adjusted in 2.1. Please upgrade your project to 3.0 or later if you would like to work with an interface sized for your monitor.

eason101 Are you using macOS? We are aware that hotkeys do not work on some older versions of Spine with the recent macOS. This is due to the fact that the OS is newer than when the Spine editor version was released at the time, so we are unable to fix the problem. It seems to work fine with Windows in most cases, so if you need to use an older version, we recommend you use a Windows PC. Please note that we cannot guarantee everything works well on Windows since 2.1.25 is a 7 year old version, so it may not work well on recently released operating systems anyway.

By the way, you had asked this question earlier in a new post, but I merged it into this post because it was the same content as your reply.