Ashley
When you pull a new instance out of the project bar, its initial properties are determined by the first instance ever created—I will refer to this as the "default instance."
As such, most Construct users create an "Object Repository" and put the very first instance of an object in there, thus establishing the default instance for that object. Modifying this particular instance is the only way we can control the initial properties of new instances pulled from the project bar.
The problem is if this default instance gets deleted, or was never established in the first place, then the initial properties of all future instances pulled from the project bar are determined by, essentially, a random instance elsewhere in the project. This is a very undesirable outcome and Construct provides us with no way of fixing it.
Here is a great example of why this is problematic: Let's say I'm working on a level and go to pull a tilemap from the project bar, expecting a clean and blank "default" tilemap. Instead, it actually created a copy of a previous tilemap from another level! Now every time I want to use this tilemap, I have to erase all of the tiles and change its size first. Now extend this problem to literally every instanced object in the project! The only reason this happened is because a default instance was not established in the object repository...but now it's too late, the only way of fixing this is to delete every single tilemap instance and establish the default instance in the object repository, or somehow locate the first-ever instance and transfer that to the object repository.
Technically yes I could create a template called "default" but I should not have to then go through the steps of making every single new instance a replica of it. This does not fix the core issue (and there's a bug where it doesn't work on tiles anyway).
So I propose one of two solutions:
A) Give the property bar a new "Make Default Instance" button in the "Editor" category. Clicking this ensures that all new instances pulled from the project bar start with the properties of this particular instance.
B) Make it so new instances pulled from the project bar automatically become replicas of the "default" template if it exists.
I have made a suggestion for this here but this is such a frustrating and longstanding editor quirk that I am hoping to bring it directly to your attention here first.
https://github.com/Scirra/Construct-feature-requests/issues/405