Picture uploading issue and also menu colour explanation issue opencart 4x

I have Picture uploading Problem on opencart 4x
I upload picture and I have it 600px x 600px and 500px x 500x and its succesfully uploading it but unfortunately is not showing upoloaded picture and when I click on it it dont show it with product. its annoying and I dont kn ow how to do it... Its like picture is upoladed but just show the name of picture without picture
Also I want to change colours on categories area and menu area and I dont know where to do it

Check your web browser's developer console for errors. Also check both your PHP and OpenCart error logs.