When Scala plugin reimports an SBT project in IntelliJ IDEA, it changes the project's JDK to 1.6. Is it a way to choose which JDK version Scala plugin sets during reimport of the STB project.
You can set JDK options like these javacOptions in Compile ++= Seq("-source", "1.7", "-target", "1.7", "-Xlint:unchecked", "-Xlint:deprecation")
, etc on SBT level in your project settings. It should help IntelliJ to use correct JDK version.