Make custom theme remember current selection

System config changes:
Before https://drive.google.com/file/d/1bkcEAn3Ov1BIWu9Ukv0HzHexeNjGCcTD/view?usp=sharing
After https://drive.google.com/file/d/1YW4qpNInycrvMfCT6s_akU2iNofnWR_s/view?usp=sharing

Go previous page:
Before https://drive.google.com/file/d/1NhAErfV_aI-B8Yra1FLzJDyw4VkhDwk1/view?usp=sharing
After https://drive.google.com/file/d/1X1lVGgiYIqhyJ2eWEuyvXL7Or_lrFoqx/view?usp=sharing

We need to handle the case of going previous page bacause users may not feel satisfied the custom theme from seeing the new preview in the naming page, then user would go previous page to update the selections.

Test: Manually
Fixes: 157631127
Change-Id: I67907f078bd47fd93ae40e12f4da4b69c5572860