Most issues can be solved by taking the following steps:
Open Google Play on your device, find Recolor and tap Update. If the button says 'Open' instead of 'Update', you already have the latest version.
You can restart your device by pressing down your power button and holding it down until your Power Options appears on the screen. Tap Restart.
After the steps above, open your Recolor app and see if the issue still persists.
Check the articles under Solutions menu to see if there already is a quick fix for the issue you are experiencing.