I activate the files associations, and they only associate themselves with files that windows already doesn't know how to open, while for the unknown ones it works as normal.
An example:
.Zip files still associate themselves with the default windows zip instead of 7-zip
same for .jpeg, .txt, .mp3 etc. They default themselves on the windows default and not on the liberkey one, even though the right click context appears.
.Blend files associate with Blender as I don't have it installed on my PC but on Liberkey

How do I solve this?

Hello AlphaWeapon .

AlphaWeapon wrote:they only associate themselves with files that windows already doesn't know how to open

Yes, this the default behavior.

AlphaWeapon wrote:How do I solve this?

Right click on KFA icon in the systray >> Associations configuration ... >> choose the extension >> Advanced >> Check "Replace the current actions for this type of files".

Thank you very much for your answer and thank you for this project - it's very useful and handy.
Is there a way to set all the extensions to replace the actions at once? If there isn't, it would be handy to have an option to do so in the future.