Reworded note

Author: Ilya Ganelin

docs/configuration.md

@@ -116,8 +116,10 @@ of the most common options to set are:
     Amount of memory to use for the driver process, i.e. where SparkContext is initialized.
     (e.g. <code>512m</code>, <code>2g</code>).
 
-    <br /><em>Note:</em> setting this with <code>conf.set(...)</code> only works in <code>cluster</code> mode (e.g. YARN deployment). For <code>client</code> driver memory should be configured in the run-time settings ; i.e. --driver-memory 2g or within <code>conf/spark-defaults.conf</code>.
-  </td>
+	<br /><em>Note:</em> In client mode, this config must not be set through the <code>SparkConf</code>
+	directly in your application, because the driver JVM has already started at that point.
+	Instead, please set this through the <code>--driver-memory</code> command line option
+	or in your default properties file.</td>
 </tr>
 <tr>
   <td><code>spark.executor.memory</code></td>
@@ -138,8 +140,9 @@ of the most common options to set are:
     and memory overhead of objects in JVM). Setting a proper limit can protect the driver from
     out-of-memory errors.
 
-    <br /><em>Note:</em> setting this with <code>conf.set(...)</code> only works in <code>cluster</code> mode (e.g. YARN deployment). For <code>client</code> driver memory should be configured in <code>conf/spark-defaults.conf</code>.
-
+	<br /><em>Note:</em> In client mode, this config must not be set through the <code>SparkConf</code>
+	directly in your application, because the driver JVM has already started at that point.
+	Instead, please set this through the default properties file.</td>
   </td>
 </tr>
 <tr>
@@ -220,8 +223,10 @@ Apart from these, the following properties are also available, and may be useful
   <td>
     A string of extra JVM options to pass to the driver. For instance, GC settings or other logging.
 
-    <br /><em>Note:</em> setting this with <code>conf.set(...)</code> only works in <code>cluster</code> mode (e.g. YARN deployment). For <code>client</code> driver memory should be configured in <code>conf/spark-defaults.conf</code> or via the run-time settings (See Dynamically Loading Spark Properties).
-
+	<br /><em>Note:</em> In client mode, this config must not be set through the <code>SparkConf</code>
+	directly in your application, because the driver JVM has already started at that point.
+	Instead, please set this through the command line option (see Dynamically Loading Spark Properties) 
+	or in your default properties file.</td>
   </td>
 </tr>
 <tr>
@@ -230,7 +235,9 @@ Apart from these, the following properties are also available, and may be useful
   <td>
     Extra classpath entries to append to the classpath of the driver.
 
-  <br /><em>Note:</em> setting this with <code>conf.set(...)</code> only works in <code>cluster</code> mode (e.g. YARN deployment). For <code>client</code> driver memory should be configured in <code>conf/spark-defaults.conf</code> or via the run-time settings (See Dynamically Loading Spark Properties).
+	<br /><em>Note:</em> In client mode, this config must not be set through the <code>SparkConf</code>
+	directly in your application, because the driver JVM has already started at that point.
+	Instead, please set this through the default properties file.</td>
   </td>
 </tr>
 <tr>
@@ -239,7 +246,9 @@ Apart from these, the following properties are also available, and may be useful
   <td>
     Set a special library path to use when launching the driver JVM.
 
- <br /><em>Note:</em> setting this with <code>conf.set(...)</code> only works in <code>cluster</code> mode (e.g. YARN deployment). For <code>client</code> driver memory should be configured in <code>conf/spark-defaults.conf</code> or via the run-time settings (See Dynamically Loading Spark Properties).
+	<br /><em>Note:</em> In client mode, this config must not be set through the <code>SparkConf</code>
+	directly in your application, because the driver JVM has already started at that point.
+	Instead, please set this through the default properties file.</td>
   </td>
 </tr>
 <tr>