A user rotates a cell phone horizontally to read emails, but the display remains vertical,...

When a user rotates a cell phone horizontally to read emails and the display remains vertical, even though the settings indicate autorotate is on, this is typically due to a problem with the phone's accelerometer. The accelerometer is the sensor that detects changes in the phone's orientation and adjusts the display accordingly. If the accelerometer is not calibrated correctly, the display may not rotate as expected.

Recalibrating the accelerometer is the most likely solution to this issue. The process for recalibrating the accelerometer can vary depending on the specific device and operating system, but it typically involves going to the device's settings and finding the option to calibrate or reset the sensor. Users may need to search their device's documentation or online resources to find specific instructions for their device.