I am bilingual, but no, I don't think my personality changes with the language I am speaking. I think that, in popular culture, the capacity of language to shape thought is overstated. It's a seductive idea because people like to think they are different in different languages, though it's more likely that they behave differently according to the stereotypes associated with different languages. For example, I always hear people claim to be more romantic in French, more light-hearted in Spanish, or more logical in German. These are all cliches. Speakers of a language all have different personalities, penchants, and proclivities. Why should speaking French make one more romantic? I've learned a few languages to a level where I can communicate comfortably, and no, I don't consider myself any different in any of them. Perhaps I will search for words or appear shyer than I am in some languages, but I'm no different.