Email signature issues in MacBook Air

This should be very easy but like I'm many things w Apple...it's not. On MacBook Air-Email signature: I have added my email & business links no problem. Added my business card… And it has blown up to a super huge size. I have tried everything to resize or even delete it ...the right click, drop down arrow, resizing in preview drag & drop options do not work… All have failed. Previous advice given on how to fix this is not correct or outdated. I'm hoping someone who had actually this problem recently knows how to resize pic down (and delete if needed). I gratefully request pls not give advice unless you have actually tried this & understand what I'm talking about. This is on my MacBook Air early 2015. Thank you for any advice tried and true.