在安装MT4时不进行设置直接点下一步，MT4默认会安装在C盘。此外，绝大多数人的电脑的系统盘都是C盘，如果你不想自己的系统盘越来越臃肿，最好把非操作系统的应用程序安装到系统盘之外的盘符。那么如何更改MT4的安装路径呢？

如果你是第一次安装，或者准备全新安装MT4

第一步，在安装MT4时，在同意许可协议那里点击设置，然后更改安装路径。

但是，原来数据文件夹就在MT4安装路径，最新版的MT4将数据文件夹和主程序分离了，分离后的数据文件夹路径在C:\Users\User_account_name\AppData\Roaming\MetaQuotes\Terminal\Instance_id，那么还是在C盘，由于你每日盯盘，看的品种又多，mt4的数据文件夹会慢慢变大，你会发现C盘还是不够用，我们需要将使用工程模式，将这个数据文件夹移动到我们刚刚修改的D盘去。

第二步，打开数据文件夹

如果你实在搞不清楚在C:\Users\User_account_name\AppData\Roaming\MetaQuotes\Terminal\Instance_id这个路径在哪里，简单办法就是运行一下mt4，然后点击“文件”→“打开数据文件夹”，这个文件路径就会自动弹出。

第三步

弹出以后关闭正在运行的MT4,然后将这个文件夹的所有文件（也就是上图所有文件夹）一次性复制粘贴到，你刚刚安装的D盘mt4文件夹，全部覆盖。

第四步

接着我们要开启MT4的工程模式了，方法：在MT4快捷方式的目标位置后加入后缀 /portable

鼠标右键点击我的桌面上MT4图标，选择属性，快捷方式，目标，默认是"D:\**********\terminal.exe" 在末尾处添加/portable保存就可以了，即"D:\***********terminal.exe" /portable

再次打开MT4，文件，打开数据库文件，你会发现数据文件夹已经在mt4安装路径重新建立了，已经不再是之前的C盘路径了。

如果你已经安装了过了MT4，要修改路径如何操作呢？

首先要找到在C盘的安装路径，默认通常在下面2个文件夹中的一个。

C:\Program Files\MetaTrader 4

C:\Program Files (x86)\MetaTrader 4

将这个MetaTrader 4整体复制到D盘以后，重复上面的第二三四步即可。

附百度图文教程:

http://jingyan.baidu.com/article/fec4bce2459b03f2618d8b9c.html

附官方英文说明:

Terminal: Changed the terminal data structure andstorage location - now, the data of each installed terminal is stored in aseparate terminal data folder.

Since the release of MetaTrader 4 platform in 2005,selected terminal installation directory was also the place where all datanecessary for work (terminal logs, templates, profiles, quotes, etc.) has beenstored. But with the release of Windows Vista in 2008, all Microsoft operatingsystems implement serious limitations of user privileges in order to protectthem against malicious programs and to prevent applications under one useraccount to change or damage the same program's data necessary for another useraccount.

Starting with Windows Vista, User Account Control(UAC) mechanism was introduced. The main idea of implementing the mechanism isthat the application's unchangeable data stored in the installation directoryshould be separated from user's data modified by this application during itsoperation. Thus, all data of each user should be stored in a separate folder.You can find more information about UAC in Windows help or the Wikipediaarticle.

In the new version, all data of a certain user workingwith MetaTrader 4 terminal from a separate installation directory are stored inthe terminal data folder. This folder can be found on a system disk (a diskwith installed Windows operating system) along the following path

C:\Users\User_account_name\AppData\Roaming\MetaQuotes\Terminal\Instance_id

where:

* С: - name of a system disk;

* User_account_name - user's account for working inWindows;

* Instance_id - unique name of the folder where theentire user's data for working with a certain copy of MetaTrader 4 terminal isstored.

"Open Data Folder" command has been added toFile menu of the terminal for searching and opening the data folder.

file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtml1/01/clip_image004.gif

The root of each terminal data folder also containsorigin.txt file where you can find the path to the installation folder of theterminal this data refers to. This allows users to reversely match eachterminal data folder with a certain terminal installation directory, forexample, in case when several copies of MetaTrader 4 terminal are installed bya user. This type of working with the terminal when the data folder isseparated from the installation one is the main mode and highly recommended forsecurity reasons.

The terminal can also be launched in the so-called Portablemode (as in previous MetaTrader 4 builds). In that mode, the data is stored andrecorded in the installation folder. To do this, use "/portable" key.For more convenience, you can create an additional terminal launch shortcutwith the appropriate name on your desktop and add the key directly to theshortcut: