DPI image quality while on page

Hi All!!!  I haven't been here for a while. I've had this question before, so now I'm finally asking. I know it's a stupid question

Sometimes in the object properties panel, if I touch an image it shows the dpi. Sometimes it doesn't. This morning it was. Now later this morning it isn't. I really need to know how to get it to show me all the time. I used search and it didn't help.

THANKS in Advance,

Merry Christmas!

~Lisa