Change the passcode on a Kindle Fire by visiting the Security section of the Settings tab and selecting the Lock Screen Password option. From this page, enter the existing passcode and then enter in a new passcode in the appropriate section, as of 2015.
The Kindle Fire includes an option that allows users to create a numerical passcode as an added security measure against unauthorized persons accessing the device. In some cases, it may be necessary to change the passcode, such as if the code becomes common knowledge or if you forget the code. The first step to changing the code is to open the Settings menu of the device, then navigate to the Security page. This page includes various additional security options in addition to the passcode function.
From the Security page, tap on the Lock Screen Password section to edit the passcode settings. When setting a new passcode, make sure to choose something that you are able to easily remember. However, you should avoid using any personal information that other parties may easily discover. For example, don't use your birthday or wedding anniversary as a passcode because both dates are easy for others to find out. Use a series of random numbers for the best level of security, then make your own mnemonic to memorize the code.