How to stop the title bar using green and black

[Enasharples]

How do I stop / change the colour combination of the title bar when I select an email
When I get the tick on the email the title bar changes from my selected custom colour to green/ black combination which I really hard for me to see 

[Enasharples]

Black ( grey ) out of green is not an awesome anything.
It is a poor combination IMHO
it has recently changed ?

[Kostya Vasilyev]

The bright green, which you seen to have the issue with, is a color (account color) that you've assigned yourself.

So, I can't tell if this is a recent change or not

Long press the account -> assign color (from popup) -> choose a lighter shade of green, perhaps.

[Kostya Vasilyev]

Oh, you must mean the icons being dark.

Did your tablet recently upgrade to Android 5.1?

If it did, that's the reason.

Something that worked since Android 4.0, all of sudden changed in 5.1.

Aqua version 1.5.5 has a fix for this.

[Enasharples]

Excellent
Yes nexus 6 with 5.1
Thank you for understanding, and providing solution.