1) Battery optimization for apps When you have connections such as Wi-Fi on while the phone is in sleep mode, some apps may still continue to use the battery. Starting from Android 6.0, battery optimization is enabled for all apps by default which helps prolong battery standby time when you're not using the phone. On the other hand, Should I Answer app needs to be active all the time to catch all calls.
a) Turning battery optimization off in apps - From the Home screen, tap the dots, and then find and tap Settings. - Tap Power. - Tap Battery optimization. - Tap Not optimized > All apps to see the complete list of apps. - To turn off battery optimization in an app, tap the Should I Answer name, and then tap Don't optimize > Done.
2) Using Boost+ Memory manager If you are using some higher HTC devices, you very likely use the Boost+ manager. In this app you should set the exceptions for Should I Answer app to let it work.
a) Adding apps to the Smart Boost exception list You can choose to set the Boost+ app to skip some apps when it runs its Smart Boost checks. - From the Home screen, tap dots, and then find and tap Boost+. - Tap Smart boost. - Tap dots > Manage skipped apps. - Tap "+", and then select the "Should I Answer" to skip. - Tap Add.
b) Optimizing apps running in the foreground Note: This feature may not be available on all phones. - From the Home screen, tap dots, and then find and tap Boost+. - Tap Optimize foreground apps. - On the Optimize foreground apps screen, tap the On/Off switch next to "Should I Answer" to turn the optimization OFF for it.