hi i need to know why there is a yello dot symbol in my phone every time

If you see orange or green indicators in the status bar 

With iOS 14, you might see an orange or green indicator in the status bar on your iPhone. These indicators appear when the microphone and/or camera are being used by an app.

• An orange indicator  means the microphone is being used by an app on your iPhone.

• A green indicator  means either the camera or the camera and the microphone are being used by an app on your iPhone.

One of the new features in Apple's recently released iOS 14 is a new recording indicator that will tell you when the microphone on your device is listening in or the camera is active. The indicator is a small yellow dot in the top right of the screen near your signal strength and battery life.

Also, if you open control center it will tell you what app was using the camera or microphone.