[All UI Elements are too small on a 5k iMac]

I've increased the font size and it helps - a bit - but the change doesn't affect the tooltip fonts as far as I can see, which remain at the original size. Can you tell me how to increase the font size here? If it can't be done, looks like an oversight as there seems to be no reason to leave these at the original and hard to read size. Can you include it in the fix?

[Lab Channels?]

I have this routine in Photoshop:

 

1 Duplicate the image

2 Change the mode to LAB

3 Isolate the lightness channel

4 Copy the lightness channel and blend it with the original RGB image

 

I have tried to replicate that in AP without success. Can it be done?