I am running 1.6.5, but the folder says 1.6.3? I just downloaded the latest version of the Arduino software (1.6.5). However, when I look into the Application Support folder under Library (I have a mac), I find that I have a folder named 1.6.3:

Library ▸ Arduino15 ▸ packages ▸ arduino ▸ hardware ▸ sam ▸ 1.6.3

Does this mean there is a hidden 1.6.5 folder that I am not seeing? 

BTW, this issue surfaced, because I am trying to fiddle around with the ADC clock speed, but it seems that nothing is happening: 

void setup() {
  #define ADC_FREQ_MAX = 1;
  Serial.begin(9600);
  Serial.println(ADC_FREQ_MAX);
}

void loop() {
}


gives me:

opamp.ino: In function 'void setup()':
opamp:2: error: expected primary-expression before '=' token
opamp.ino:4:18: note: in expansion of macro 'ADC_FREQ_MAX'
opamp:4: error: expected primary-expression before ')' token
opamp:4: error: expected ';' before ')' token
expected primary-expression before '=' token
1.6.5 is the version of the Arduino IDE.

1.6.3 is the version of the Arduino SAM Boards package that you have installed.


  Does this mean there is a hidden 1.6.5 folder that I am not seeing?


Library/Arduino15 is where your preferences.txt file and Boards Manager index files are stored. Library/Arduino15/packages is where hardware packages installed via Tools > Board > Boards Manager are stored. The Arduino IDE will be located elsewhere on your hard drive. If you need to find it here is an easy way:


Tools > Examples > 01.Basics > BareMinimum
Sketch > Show Sketch Folder - this will open the Examples/01.Basics/BareMinimum subfolder of the Arduino IDE installation folder.



  BTW, this issue surfaced...


That's off the topic of your question and already answered in a comment on your question so I will refrain from answering it.