Introduction
Code Composer Studio (CCS) allows for customization of several settings related to the editor and GUI. These settings can be found under menu Window->Preferences. Be sure to click on Show advanced settings at the bottom of the pane to see all available settings. The search box at the top can be used to further filter down the available settings.

This article describes where you can find and customize some of the more commonly used settings. It assumes you have already clicked on Show advanced settings to expose all settings. If you are looking for something that is not explicitly mentioned in this page, it is still likely available somewhere in the Preferences page.
Editor
Some editor settings can be found under General and some under C/C++.
Insert tabs instead of spaces
The tab policy for C/C++ source files and plain text files can be changed, but from different settings.
The tab policy for C/C++ source files can be changed from Window->Preferences->C/C++->Code Style->Formatter.
From here you can either click Edit... to edit the existing CCS Profile, or click New... to create a new profile based on the CCS profile (probably the better way to go so you can always revert back to defaults if needed).

Edit the new profile to make changes to the tab policy.

The tab policy for text files can be changed from Window->Preferences->General->Editors->Text Editors.

Typing preferences
Auto-closure of double-quotes, brackets, etc. during typing can be enabled/disabled from Window->Preferences->C/C++->Editor->Typing. The "Strings" checkbox is for auto-closing double-quotes.

Color
Color preferences and themes can be customized in a few different places depending on what is required. Settings can be found under:
- Window->Preferences->General->Editors->Text Editors
- Window->Preferences->General->Appearance->Colors and Fonts
- Window->Preferences->General->Editors->Text Editors->Annotations
- Window->Preferences->C/C++->Editor
- Window->Preferences->C/C++->Editor->Syntax Coloring
To choose a theme different from the default, such as Dark or Light theme, go to Window->Preferences->General->Appearance and select from one of the available themes.
Code Folding
Code folding can be set from Window->Preferences->C/C++->Editor->Folding. Enable the desired settings and then check the box "Enable folding when opening a new editor". Close and reopen the editor for the settings to take effect.
This video shows a demo.
Viewing source files side by side
This video shows how you can view source files side by side in the editor.
Other Customizations
File associations
If you have source files or linker command files with extensions that are not recognized by default, you can add them under Window->Preferences->General->Editors->File Associations as described in this forum post.
Console view
The console view settings can be customized from Window->Preferences->C/C++->Build->Console (for build console) and Window->Preferences->Run/Debug->Console (for debug console). Here you can modify things such as size of console output, output text color etc.
Shortcuts/Key Bindings
Some menu options have keyboard shortcuts assigned by default. You can change these or add your own from Window->Preferences->General->Keys.
Any customized keyboard bindings will be applicable to all projects in current workspace. To export keyboard settings and import them into another workspace, you can use the File->Export->General->Preferences and File->Import->General->Preferences menus in CCS as mentioned in this link.