The sa password for our Kaseya server is currently unknown. We can login to SSMS with Windows Authentication mode, so we can update credentials as needed. What would be the impact of changing the sa password within SSMS?
Kaseya does not use the sa password during normal operations, so changing this will have no impact at all.
You do need the sa password, or equivalent when running KInstall.exe, either to install a patch or run a full update, but that is only used to validate your access rights at that time.