This week we have two questions about Outlook window sizes. The first one affects users with Surface and other tablets and laptops with smaller screens. Problems caused by screen resolution and non-default display settings has been an issue with Outlook, often with buttons and parts of dialogs missing.
Outlook items always open full screen
Every time I open an email, calendar item, contact or note in Office 365 Outlook on my Surface tablet, the item opens full screen. This occurs even though I resized the item window significantly smaller and closed the item.
This is the result of using a high screen resolution on a small screen. The user can't read the tiny text and changes the display settings to make everything larger. To check your settings, go to Control Panel, Display and look at the Change the size of all items setting. If it is set to 150 or higher, Outlook windows open at full screen, lower than that and the window sizes hold as expected. (If you see a slider instead of the percentages, tick the box to choose scaling for all displays.)
Outlook windows won't resize
The second user's problem was that Outlook is either minimized or maximized. Clicking Restore minimizes the window.
When the problem isn't due increasing the display or lowering the resolution, it's because the window was pushed off the edge of the screen. Changing the screen resolution may have caused it, but you can fix it without changing display settings.
There are two ways to fix it: use a Windows command to rearrange all open windows and bring Outlook back on the screen or edit the registry to reset the Outlook window to the default size and location.
Right click on the Windows Taskbar and choose from Cascade windows, Show windows side by side, or Show windows stacked. If you like your windows arranged in a specific side and position on the desktop, you'll want to close all other windows before using these commands.
Outlook window position are stored in the registry, in a value named Frame. Each Outlook window has a Frame value in their registry key. To get the main Outlook window back to full size, find and delete the Frame value under HKCU\Software\Microsoft\Office\xx.0\Outlook\Office Explorer, where xx is your version of Outlook. If you have a value called Namespace, delete it as well. When you reopen Outlook, it will open at full screen and recreate the Fame value the next time you close Outlook.