XML : Resizing Image Buttons and Image Views on a XML Page

So I have this XML layout page, but when i put it on a bigger screen nothing resizes, i was wondering how this would be done. Can it be done through the XML or Java, or both?

This is my layout code

  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"  android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"  android:paddingRight="@dimen/activity_horizontal_margin"  android:paddingTop="@dimen/activity_vertical_margin"  android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainPage"  android:background="@drawable/appbackground3"  android:id="@+id/HomeLayout">    <ImageButton      android:layout_width="120dp"      android:layout_height="120dp"      android:id="@+id/PlayBtn"      android:background="@drawable/mybutton2"      android:src="@drawable/playbutton"      android:layout_alignParentBottom="true"      android:layout_centerHorizontal="true" />    <ImageView      android:layout_width="500dp"      android:layout_height="120dp"      android:id="@+id/TitleImg"      android:background="@drawable/title"      android:layout_alignParentTop="true"      android:layout_centerHorizontal="true" />