The colors are merely of symbolic value, nothing which is more important and deeper than this, obviously not something that will damage you for not doing it as an optional thing. Candles are used for stimulating emotion and inspiring one to feel what they are casting.
Some people don't even use colored candles, some carve sigils into them and that works for them just fine (I use this for my own spells and my own rituals as well).
The thing I recommend you personally is to go with what you feel necessary and what you're most comfortable with for your own spells, and rituals... Candle magic or using candles in magic is not an inflexible or rough practice, so if the white candles with colored coating works for you then they will obviously work for the circle casting. If you prefer solid colors then by all means, use the solid the ones instead. As I say, just do what you will.
As for the hard time finding your own posts. You can do some things :
- Going to your own profile and checking out the history tab.
- Marking your own thread as a favorite after posting it, later going to your favorites and seeing what's going on with your thread.