I almost complete agree with Kate Paulk. Almost because I would say: If you don't have fun during work - change your job. In the last years I saw many (ok they were mostly trainees but hey..) people who didn't have fun in their given parts of software engineering and their useful output was much lower than the output of those who had fun doing their job.
For myself I also started as a developer after my traning as a software engineer. In my freetime I'm in a leading position of a small browser game and so I don't only code but also do requirements enineering and QA. After some time I noticed for myself I'm stronger in this parts of the whole process than in writing code. So I was happy when I had the chance to switch from development to QA. I noticed that I can can analyses problems very well and with my experience as a developer I find many bugs my QA partners (who have no experience as a developer) don't find (keywords: experience driven testing / error guessing). Furthermore my knowlegde helps me to write automated tests like load test, automated GUI tests and so on. I also noticed in several testing courses (e.g. of ISTQB) that many tester who don't have experience in developing (may) have certain problems in understanding.
To conclude this and came back to the question:
- If you have more fun in testing that's the most valuabe point. As more fun means more motivation and (much) better output of your work.
- With your experience as a developer but your strengths in testing you are also more worth for the company as you can generate better output again. Maybe you can also improve QA in general due automated testing and so (see part above)
So: Tell the truth and make the advantages of your switch from developement to testing clear. Any wise boss will understand it and you'll get work :)
Good luck anyway (you always need a bit luck) - and remember: It's all about fun and motivation at work! Not about the money!