Pictures that can

Hello , i have again started to contribute more to the forum. My question is how is it that some pictures on forum has the expanding arrow in bottom right hand side of picture in able to enlarge it and be able to download it and some do not.
How would this be done?

Obviously i am only uploading pictures without that option. I’ve also noticed when this is done the pictures are smaller and assuming it takes up less bandwidth.
Assistance would definitely be appreciated.
Philip

A quick look through some of your posts it seems that all of yours are big enough where they get resized and have the option to expand.

But as a general rule, if the pictures are nice and big they get resized to fit on the screen with the option to expand.

Ok thanks Aaron ! As i went back after i already posted question. I noticed my fault. What i need is a better camera. As it seems when i expand my pictures they get ugly unlike others that post beautiful pictures. Thanks again Sir. Oh and back in the day when u helped me with Keith Lampears question that i had. You were absolutely right. After my purchase i was able to enter in my log in information.
Thanks again
Philip