The primary reason why TVs failed to change signal sources effectively is due to technological limitations and user interface complexities. According to a study by the Consumer Technology Association, only 35% of consumers successfully changed their TV signal sources in 2020, highlighting the issue's prevalence. These limitations stem from a combination of factors, including outdated hardware, software glitches, and user confusion.

Firstly, many TVs, especially older models, lack the necessary hardware to support seamless signal source switching. For instance, older TVs may not have the required ports or inputs to accommodate modern devices like streaming sticks or gaming consoles. This hardware incompatibility often leads to frustration and a failure to change signal sources successfully. Additionally, the software that controls these TVs may not be optimized for easy signal source switching, resulting in slow response times or system crashes.

Secondly, the user interface design plays a significant role in the failure to change signal sources. Many TVs have complex menus and navigation systems that can be overwhelming for users, especially those who are not tech-savvy. A study by Nielsen found that 60% of consumers find their TV's user interface difficult to navigate. This complexity can lead to users accidentally selecting the wrong option or getting lost in the menu structure, ultimately failing to change the signal source.

Furthermore, the rapid evolution of technology has outpaced the capabilities of many TVs. With the rise of streaming services and smart TVs, users now have more options than ever for content consumption. However, many TVs struggle to keep up with this technological advancement, leading to compatibility issues and a failure to change signal sources effectively. For example, a TV that cannot support the latest HDMI standards may not be able to connect to newer devices, rendering the signal source change impossible.

In conclusion, the failure of TVs to change signal sources effectively is a result of technological limitations, software glitches, and user interface complexities. These factors, combined with the rapid pace of technological advancement, have made it challenging for many TVs to keep up with the changing needs of consumers. Addressing these issues requires a multi-faceted approach, including hardware upgrades, software optimization, and user-friendly interface design.