Tor browser sets the highest security level. The website can be opened normally, but the mixer cannot be used, and the plug-in image cannot be opened. Tor browser sets the standard security level, and everything can be used normally
As @DroomieChikito mentioned above, there is not any security level within Tor I am aware of. It just builds circuits you can use.
What do you mean by "mixer cannot be used". Is it like you get an error message?
I am not sure what "plug-in image" refers to. FoxMixer has nothing to do with plugins you might be using within your browser.
And you say that for the standard security level it works, so why not just go with that?