How to change the build gradle to an earlier version (android studio)?

I'm creating a project that runs in the version of android studio 3.1, and I have this old version of android studio but the build gradle is up to date and I can not make my codes run I do not want to change my codes or adapt I just want to go back to old version can anyone help me? I have already tried to give up and install again and still does not change anything in build.gradle.

  

How is it now?

android {
compileSdkVersion 28
defaultConfig {
    applicationId "com.example.t_gamer.myapplication"
    minSdkVersion 16
    targetSdkVersion 28
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }

  

How I want you to stay

android {
compileSdkVersion 27
defaultConfig {
    applicationId "com.example.t_gamer.deepcooeesite"
    minSdkVersion 16
    targetSdkVersion 27
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
productFlavors {
}