We are sorry for the delay in response to your query.
As said that some of the texts converts successfully, other remains as text. So there are couple of possibilities-
1- The pdf file you have converted to word might be a scanned pdf which doesn't contain real text.
If it contains text also, then you can click on "Enable all features" option that appears on the top right side of the word document.
2- If your original pdf has images rather than text, then after converting to word document the images would remain the same and that wont be editable.
Hope this helps!