I don't believe you can set a default color Tai. The group objects can be selected and from there an entire group can be colored, but you are probably wanting lower thirds to be one thing, full screens another. Correct?
If so, the process would be a bit tedious. Group everything, color the groups, and then distribute within the sequence, but like I said, that's a bit of work.
Also, you posted the same topic several times so I deleted those other posts.
#XPression