linux - Raspbian (debian) file permissions do not persist after setting with chmod -

I am new to Linux because I have just purchased a raspberry when I change the permissions of an .i file Chmod, so that I can execute it, and finally add -v: "chmod a + x test.py -v" changed permissions have been changed "rwxr-xr -x" then when I say "ls- L ", then there are permissions because before I used chmod. "RW-R-R-O" What's going on? Thanks

I was trying to give the "execution" privilege to the USB memory stick when I He took them to the Home Directory and I was able to change them. So, maybe their place made the cause of my problem Peter