In case that description is as unclear to you as it is to me on a second read, here’s an example:
Say I have the following (I have manually inserted line breaks to imitate the problem – so this may not look right on all devices)
Phasellus laoreet lorem vel dolor
tempus vehicula. Paullum deliquit,
ponderibus modulisque suis ratio
utitur.
Quisque ut dolor gravida, placerat
libero vel, euismod.
But when I type the next word in the second paragraph, notice how the justification changes on the first paragraph:
Phasellus laoreet lorem vel dolor
tempus vehicula. Paullum deliquit,
ponderibus modulisque suis ratio utitur.
Quisque ut dolor gravida, placerat
libero vel, euismod. Mag