(Hopefully easy) science lesson incoming...
Light on the blue/violet end of the spectrum is more likely to interact with molecules in the air, which causes (predominantly) blue light to be scattered in all directions wherever there is air in the atmosphere. And if you look up in the sky at daytime there is a lot of air between you and the blackness of space that "reflects" blue light in all directions, including yours.
That is why the sky is blue. In simple terms, blue sunlight is "reflected" everywhere by the air when the sun shines on it.
The sun and the air just around it looks yellow because a significant part of the blue light is scattered everywhere by the air between you and the sun before it reaches you, leaving the red/orange/yellow/green light, which together look yellow.
But when the sun is near the horizon, the sunlight doesn't take the short way through the atmosphere. It has to travel through a lot more air to reach you, which means most of the blue light and even a significant part of the green light is scattered away by the air before the light reaches you, leaving only the reds, oranges and yellows we know and love from sunrises and sunsets.