How to - trying to mockup up dress in photoshop - tools don't work properly

hi there, i'm trying to create an outfit mockup that is not straightforward. i've watched the only 2 videos i could find for complex mockups and i can't get past the basic stage of selecting the correct tools (which i have but they don't work the way the person in the video shows it to work) which is lasso and object selection. i have the selection set to lasso and it will not change to lasso it's a cross with the square when it should be a lasso with a square, there's gotta be a secret thing i'm missing, these videos make big assumptions and never go into detail. please help. thanks bec.

https://www.youtube.com/shorts/FJfLaLDMPjQ