I wish I could change the color of the file on the main screen to something other than blue. It would be cool to change the color I chose myself. It's time to distinguish between all files....

1. default paper color
At the moment we can choose one of two: white or strong yellow.
In my opinion, the yellow one is too strong - of course, this is just my opinion, but adding the possibility to choose a paper with a slightly less yellow color would be something great.
I think the way to have a cool yellow color is in Notability. There yellow seems to be nicer - better perceived by the eye.

2. color of the application bar.
Right now we have something like light navy blue - it's a bit sad and a very office color.
Could you consider adding the ability for users to change this color?

I know these are, frankly, minor things, but adding the ability to change them could improve the look of the app.
These are my comments.

Currently, the toolbar remains purple, which can be distracting when everything else is white. It'd be good to be able to customise that colour to white or black or something more neutral or subtle, or even colour code the tool bar based on notebooks (like theme colour). its all about choices... and the purple right now shouldnt be the only option

Please allow us to change the color of the blue header bar or fill the entire screen with our page

to change the top color of the banner in the app

Please, the dark blue menu bar, while in drawing mode, is pretty distracting, and the number one reason I almost didn't stick to goodnotes..
At least make it dark grey or plain light white, or at least create a number of some new inter-changeable menu designs, that we could "buy" in the app, if not for free...Dark mode doesn't help here..

Add more theme colors for the borders. When you open up a notebook, the top color is only blue with no option to change it, it would be nice if we could change the color of that to makes things looks a little bit nicer.

Yes please! I would love a mint option

The purple-blue colour of the tool bar is not idea for corporate sessions, and does not fit with the dark mode scheme.

Could you give us the ability to change this colour? Alternatively, if it is dark mode, the colour of the tool bar should be a shade of dark grey or black.

The way I use GoodNotes (and have for 2 years) relies heavily on colour coding. It’s a creative process to make notes and the new blue colour of the navigation bar inhibits the feeling of starting with a blank canvas. (Like a painting app with a blue UI.) It seems to interfere with my colour associations.

Please add a toggle in the settings to turn the navigation bar grey like when the pen is disabled.

I want to change the color of the part above the toolbar!

I would be nice to have different themes to customise the toolbar colours, the icons colours and the main screen look

I agree with this, everything in white is very disturbing and hurts the eyes. Consider this is an app that one usually uses for long periods of time, if you are in a class taking notes, reading or annotating pdf, so the way it looks should be comfortable or at least provide other options.

background options would be nice too. the white is a bit blinding

Yes, I think a dark color would be a good alternative too, but the interface could lose its freshness. I made some example with the dark background visible under the PDF page.
http://cl.ly/image/3F3T0M0D1h36/Dark.png
http://cl.ly/image/190n42212645/Dark%20(home).png

please give us an option to change the toolbar (and background) to another colour (eg. black/dark grey similar to safari in private mode would be a good alternative as well)

I like the new iOS 7 design, but I think the white color of the toolbar is a bit 'too "flat" and the icons aren't very visible. So I'd like a colored toolbar that can create more contrast.