What pronoun should theses use?
I used “we” (except for the acknowledgements). It’s what I’m used to when reading academic writing. Anything else wold seem weird to me.

Although the primary reason was that It was a stapler thesis and that is what the papers I was copying from used. It would have been too much effort to change it.

Customs may vary by field and country. The best thing to do is look at a few theses coming from your department and copy their style.