As the documentation says:
Using with the run command There are a couple of special things to know about configuration when running your application with the run command.
Extra devSettings You can configure extra settings for the run command in your build.sbt. These settings won’t be used when you deploy your application.
devSettings := Map("play.server.http.port" -> "8080")
https://www.playframework.com/documentation/2.4.x/Configuration
But when i run activator a type error is thrown:
Error:Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=384M; support was removed in 8.0
[info] Loading project definition from /Users/carlos/Documents/workspace/qrsoft/manager/project
/Users/carlos/Documents/workspace/qrsoft/manager/build.sbt:27: error: not found: value devSettings
devSettings := Map("play.server.http.port" -> "8080")
^
[error] Type error in expression