How do I turn off rounded corners on my OnePlus 6T and How do I get it to stop closing apps?

[Android Central Question]

The rounded corners trim information off on some apps. I have no interest in rounded corners. Screen caps show the whole area but it's being trimmed in software. I have no interest in making my SmartPhone like an old dumb tube TV.

My 6T has more RAM than my old phone, but it closes apps very quickly, after only a few minutes in the BG, requiring a re-launch. Why is this?

 

[pontiac005]

To save battery