thanks for your post.
Judging from your description, I assume that you are using Internet Explorer 9. There is currently a known issue in WP-Table Reloaded, due to which the text fields are very small. I will release a new version with a fix soon (don't know when yet, as I'm busy with other stuff at the moment).
Until that happens, I suggest that you switch to a different web browser when editing tables, like Firefox or Google Chrome. With those browser, the text fields will not only be displayed in the correct and wider layout, but you actually have the option to simply change the width by draging the edges of the textfields.