Which syllable to stress when conjugating verbs

Question

Example necesitar. The stress is on the last syllable. [neh-seh-see-tahr’] Are the conjugated forms treated as individual words or does the stress stay with the last syllable? yo necesito [neh-seh-see'-toh] or [neh-seh-see-toh'] él necesita [neh-seh-see'-tah] or [neh-seh-see-tah'] nosotros necesitamos [neh-seh-see-tah'-mohs] or [neh-seh-see-tah-mohs'] ellos necesitan [neh-seh-see'-tahn] or [neh-seh-see-tahn']

Answer 1

Azabache gave a great answer but I think you might be able to further benefit from this: http://vidadescott.blogspot.com/2013/03/los-acentos-leccion-y-practica.html

Answer 2

The general rule to follow is to stress the second to last syllable when conjugating verbs in the present tense.

Yo neces-i-to

Tú neces-i-tas

Él/Ella neces-i-ta

Nosotros necesit-a-mos.

Vosotros* (an exception) necesit-áis

Ellos/Ellas neces-i-tan