Understand the idea
Unexpected battery drain can come from screen brightness, poor signal or an app running in the background. One short observation is rarely enough to identify the cause.
Put it into practice
Review system battery usage over a representative period. Restrict unnecessary background activity and compare usage after changing one setting.
Know the limits
Battery-saving modes can delay notifications; account for that before depending on a time-sensitive alert.
The wider context
Stable devices make online reading and practice easier, but performance settings cannot change the odds of a game. Back up important data before disruptive troubleshooting. Use manufacturer documentation for model-specific steps and keep software within supported, trusted distribution channels.
Your next step
Use the practical step above only where it fits your situation. Before an account-specific action, check the current instructions from the service or device provider involved. Write down what you observed and what remains uncertain; that makes a follow-up question more useful.