Its the difference in displays resolution. Your internals display most likely has a High DPI resolution and your external displays has a low resolution display. If you use Photoshop 2X UI scaling so you can see Photoshop UI on your MacBookPro Display Photoshop will also scale your external display 2X so Photoshop Palettes will display huge on you external display. To get around this problem do not use Adobe Photoshop 2X UI set UI scaling to 100% not Auto or 200%. Have Photoshop UI on your external display and edit your image in floating windows on the macbook's display.
Lightroom I do not use however, it works OK because it does not have a 2X UI option it uses your OS scaling. I do not use Mac OSX on windows scaling is set per display. Mac most scaling is likely the same. So OSX is not scaling your External Display it running at its native resolution 100%. Your Macbook Display is most likely scalled 200% its running at half its native 100% resolution.
Is this too much to ask?
You stated what you want but not how you fail to achieve that. (edited)
I work on an iMac (Mac OS 10.12.4) and in Photoshop (2017.1.1) the Canvas, Toolbox and menu reside on the EIZO screen while most Panels reside on the iMac screen, so the issue does not seem to be impossible, but you have not provided terribly detailed informations …
What are your OS Display Preferences for example?
And how about versions?
Thanks for the responses! JJMack, what you have stated makes sense to me. I am not able to see where I should change my settings for the display and scaling. Is this under System Prefs on the Mac or prefs in PS?
I am currently using an Eizo ColorEdge CG222W monitor along with the MacBookPro 2015 Retina, 15", running 10.12.5.
The built in Retina resolution is set to default. The Eizo is set to default, which I think is 1680x1050?
Thanks to both of you for your help so far!
I think you would be fine with you Mac default settings for display scaling. What you do not wan is Photoshop UI 2X scaling. I use Windows so I do not know where you set Mac display scaling.
In Photoshop Preferences you want Photoshop's "UI Scaling" set to 100% not Auto or 200%.
On Windows I have Windows scale my 24" 185DPI $K display scalled 200%. Photoshop Tell Windows it will handle Scaling so Windows does not scale what Photoshop displays on information on my 4K display. Windows will scale what other applications display on my 4k Display. I create mt wall paper in three section at two different scales two sections for my two 100DiP displays and one section for my 185 DPI 4K display.
Wow. Sweet setup you have there! I went to my PS prefs on my Mac (they looked just like yours on the PC) but the UI scaling is grayed out. I am not able to change it from auto to 100%. Any ideas how to get around that? Thanks for your time and expertise.
What are your OS Display Preferences?
As for the menu obstructing part of the image that seems strange but have you tried using another screen mode (F)?
For the OS display preferences it just gives me Default or scaled.
Then, it is default or then..... larger text or more space. I had already tried scaling it smaller but no luck.
I will try another screen mode but the weird thing is the image box is justified to the top left corner instead of letting the menu bar and tools be at the top and sides.
My Apple machine is brand new so i could actually talk to customer support but it seems like this is a PS issue not really a Mac issue. I have not been able to find a way to actually speak to someone at Adobe (in contrast to Apple). Thanks.
What is the Arrangement setting?
Please post a screenshot.