Can not change certified mode

Hello,

my company uses plugins with Acrobat DC. We had to install the plugins on a new computer which worked but they did not show up in tools in Acrobat DC. 

The provider of one of the plugins told us that in the Acrobat settings in "general" the certified mode must have the status "no". We are not able to change this setting as it has the status "yes" on that computer. The plugins are working on other computers where the setting has the status "no". 

How can I change the certified mode to "no"? Everything that was posted on this forum unfortunately has not worked for us.