If you manage many accounts, it can be quite a hassle if you want to modify multiple accounts captions/DM messages/etc... . This can be resolved by using custom variables.
Custom variables allow you to use self created variables so you can insert them anywhere in GMT2 with a text box.
To get started, create a text file somewhere on your PC. Now to syntax to create custom variables is Key=Variable and then simply separate multiple key variables pairs by placing them on their own line.
So e.g. A=My custom variable would be a simple example. Do note that your variables keys can't contain any spaces, so Variable Two=My variable would not be allowed and would have to be VariableTwo=My variable.
Once you have created your text file. Simply save it and close the file.
Now open GMT2 and click on the cogwheel top right. Here you will see the option to enter the path to your custom variables text file. Click on "Select File" and select the text file you created.
Now we are all do, inside GMT2 simply type [KEY NAME] to access your variable. So in our example it would be [MyFirstVariable].
If you wanted, you could now open the text file and edit the variable and simply save the text file and the variable value would automatically change without you having to do anything!