In Service Studio, Allow double-click to toggle entity attribute property values.

e.g., "Is Mandatory" = "No" (by default).

Double-click the "No" to toggle it to "Yes".

Double-clicking the wide "yes" bar background is faster and easier than locating the drop-down arrow, and then selecting the other value. 

Also, when navigating via tab, consider allowing the "space" key to toggle the value. This is also faster than having to find the Y or N key.

For property values with more than two options, just iterate through the options.

PS: As a new user to Service Studio, double-click and space were the first options I tried in both navigation scenarios.