Change voice prompts (System Prompts)

[Chichi]

Hello,
i have 3cx installed on a windows server.
By default the system prompt is set to Standard English Prompts Set, in my clients opinion its a very annoying voice.

i have tried to change this to the UK English Prompts Set, restarted the services, but no joy, i also restarted the server however the american accent is still bothering my client.

Can anyone confirm if i am missing something here?

thanks in advance