Use command-line options to edit registries with regedit exe

HKEY_LOCAL_MACHINE (shortened name HKLM). Data in this root key relates to configuration information for the computer or any user.

HKEY_USERS (shortened name HKU). This root key holds all the actively loaded profiles for users on the machine.

HKEY_CURRENT_CONFIG (shortened name HKCC). This root key holds hardware profile information the machine calls during system startup.

Below each key can be multiple subkeys and values. Not every application requires a subkey.
Oftentimes, Microsoft will direct administrators to mitigate a pressing security issue in Windows by modifying subkeys in the registry by adding new registry values -- also called data entries -- or modifying or existing ones.
One common Windows registry edit is changing the file association for a certain file type so it opens with a specific application. For example, if you want .html files to open with Google Chrome rather than Microsoft Edge, you can adjust those settings in the file extension area of the Windows registry.
Regedit.exe uses
Regedit is the GUI-based tool built into Windows for editing the Windows registry. To start, type regedit from the Windows run or search box.
Regedit gives a visual representation of the Windows registry, using a dual-pane layout with the root keys and subkeys in the left pane and the values for the selected key or subkey in the right pane. You can import or export registry subkeys and values from the File menu. From the Edit menu, you can create a new entry in the registry, check the permissions for the selection, delete or rename the selection, or copy the key name. You can also run a search from this menu.
Right-clicking in the different sections let you add a new key, modify an existing one or delete a key.
The regedit registry editor is a GUI-based tool that displays the hierarchical layout of the Windows registry. It also includes several command-line options.
Due to its importance to the Windows operating system, you should export a backup of the registry in case you need to recover from a problem. Use the export function in the regedit File menu to make a backup of the entire registry or just the section you plan to edit. This will create a .reg file. If a problem occurs, you can double-click on that .reg file to restore the original settings.
Microsoft released its first 64-bit Windows Server version with Server 2008 and its first Windows client 64-bit version with Windows 8. The default version of regedit in the latest versions of Windows can open both 64-bit and 32-bit registry keys for backward compatibility.