Shrinking Model

I modeled a shark for a tutorial I am following. I am having a problem that the shark keeps shrinking into a squashed up shape. In object mode the dimensions box has a yellow background, which I don’t normally see when I model things.

Can someone tell me why the background is yellow and how I can stop the shark shrinking. Otherwise I will have to start again. Thanks.

I had thought that my original request didn’t get uploaded. I didn’t spot your first response, sorry. Other forums I am in let you know if there has been a response. I don’t recall seeing an option for email notification of a response. Is there one?
In regards to the problem I am new to animation and the shark shrank as I followed the tutorial’s steps to do the animation. Thanks for your help.

It is a little hidden in in the corner, but you can subscribe to threads.