Customize Top Bar of Apps

hi everyone,
what i would like to do is customizing the toolkit top bar for our studio,
but after a bit of search i failed to find where exactly i need to to this.

Could someone help me where i.e. i can find the SG Logo and the arrow icons that are shown in the attached image? i searched our whole config, core and sg desktop version for all pngs and found the arrow in the core (i.e.) But swapping it with something different didn’t change anything, so i am a bit confused here.

Thanks for clarification in advance!