Issue Subdomain has 2048Bit Let's Encrypt Certificate despite panel.ini with rsa-key-size = 4096

[doofesohr]

• OS: ‪Ubuntu 18.04.2 LTS‬
• Plesk Onyx 17.8.11 Update Nr. 55

It works for a subdomain I created quite a while ago. Created a new subdomain today which in itself works perfectly fine. But I'd like it to use a 4096 Bit certificate too. This page tells me to set a parameter rsa-key-size = 4096 in the panel.ini.
I located said ini-file at /usr/local/psa/admin/conf. And the parameter is already set. Why is it not working? Are there any other places for the panel.ini?

Greetings,

doofesohr