In IntelliJ, I&#39;m getting this strange error message when I try to build from the build menu

&gt; Error: java: release version 10 not supported

I don&#39;t understand this, since in *Project Structure*, I have these settings set: 

&gt; Project SDK: 9.0  
&gt; Project Language Level: SDK Default   
&gt; Module Language Level: Project Default (both modules)

In my pom.xml files, I have these properties set in both modules: 

    &lt;maven.compiler.source&gt;9&lt;/maven.compiler.source&gt;
    &lt;maven.compiler.target&gt;9&lt;/maven.compiler.target&gt;

I have no idea why it&#39;s trying to use JDK 10 for anything, but I still get that message. 

I&#39;d be happy to use JDK 10, but my project doesn&#39;t work in that version, so I&#39;m going back to see which versions it works in. I have SDKs installed for version 1.4 through 10.
 
I&#39;ve also tried building using JDK 1.8, but I get a slightly different error message:

&gt; Error: java: invalid target release: 10 

I&#39;ve found that I can build from the command line using JDK 9, but I need to build from my IDE.

Can anyone tell me how to build my project using JDK 1.9 or 1.8?

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IntelliJ: Error: java: release version 10 not supported