Dpi problem

Hello I'm using Photoshop (21.2.3) on Windows 10.
I'd like to save an image .jpg with 300 dpi, and I'm using the "save as" button... but I find the image in the folder with 762 dpi (I draw on files 7100x5000 pixels, 300 dpi  in general).
Same thing when I'd like to save in 150dpi... I change the dpi in the "image dimension", down in the left corner I have always the correct dpi I'd like... but when I "save as" I find the image with 381 dpi
What am I doing wrong? Thanks!