How to change project language level for all project in Intellij

Question

I am using Intellij. It is good, but when I create a new project or import a project the default project language level set to 6 (@override in interfaces). But I want to set

Answer 1

Same problem but slightly different solution. IntelliJ (2018.1.15) gave me the option to Set Language Level to 6 which I accepted. This added the following to the project .iml file:

    
        
            org.apache.maven.plugins
            maven-compiler-plugin
            
                6
                6
            
        
    

I was then able to update source & target to 8.