Using the backup addon in Kodi is a safe option. Make sure in the addon settings though you select the path that you will remember for the backups to be stored. This, depending on how you've customised Kodi can be a large file! I have one at 1gb! Also take note, when you've made your backup, go into file manager in Kodi, on one pain search for where your backup is located, on the other pain go into the profile directory (make sure in Kodi main settings that view hidden and system files is turned on) in the profile settings folder pain in Kodi you should see a guisettings.xml file, copy that to where your backup is located.
When you restore your back up, install the skin that you configured to you customisation and notice no settings have been applied. Exit Kodi, then use esfile explorer, locate the guisettings xml where you made your backup save directory, copy that to the Kodi directory located on the android box, again make sure the view hidden files is set to view in es. Exit es then load Kodi and it will run from that xml file.
Sorry if the post doesn't fully make sense, just done a night shift. If you need more help let me know.
I know from experience not copying that xml file can be a pain.
Edit to add, another option in Es file explorer copy the whole Kodi directory to an external device, HDD, SD card etc. Again be aware that this could be a large file!