Hi Ayesha,
There is a maximum limit of 250 characters for each word slide, and this is why the texts you were trying to enter do not fit on screen.
Also, especially if you plan to share the files you're working on now with other LR users, you may need to take into account the fact that the amount of characters that can fit on screen will also depend on the screen sizes of each person's computer / notebook. So although there is a maximum character limit, this may not always apply to those who have small screen sizes.
We have two suggestions for you:
1. Split each line of text into two or more slides -- perhaps you can have 1 sentence or clause per slide
2. Keep in mind to not have exactly 250 characters for each word slide, keeping a few character spaces unused, as a workaround for those who have smaller screen sizes
I hope this helps!