Use a button.
Reset to default is no state, so it should not be a switch, checkbox or radio button.
Resetting to default is an action and the best element for actions is a button.
If you want an indicator if a field is still the default, separate it from the action, e.g. give the input field a lightgrey background until it is changed and reset it to ...
I would suggest you use the plural form especially if you anticipate your users selecting multiple values over time. Also looks cleaner (just as you mentioned) and would fit perfectly when the user eventually selects multiple values.
The user needs to know that:
Certain fields have default values and they will be saved along with the form
Default values can be edited
If you have the default Title and Description as text and allow the user to hover and see an edit field around it they will understand they can edit that field. Having them as text on the first instance will make them ...
To add to the already good answer, would it be possible to prevent the user from making any wrong choices to begin with?
Is it possible that when one field is filled in, the invalid options are no longer selectable in other fields?
This may not be possible in fields like username and password.
But in other fields perhaps it is.
It would be almost like ...
Question: Link, checkbox, or switch? Answer: None of the above.
User generally expect links to navigate –that is, take them to a new location. Switches and check boxes set attribute values or states –that is, what something is like. That would be suitable if the app simply switched the text from one characteristic to another (e.g., bold versus normal font), ...
IMO, you are both correct. The engineer is doing their job by giving their insight. Meanwhile, the designer should advocate for user empathy. But here is some ammo for you, Dennis: is this validation list more of a SIGNAL or more of a NOISE? You can measure this question by testing and asking a small group of users. Let the results speak for themselves. If ...