When you have created a new project, or loaded an existing project into Pencil2D, where does the program get the filename it attempts to use.
I realise that if I supply one, Pencil2D uses it as one would expect. But if you don’t Pencil2D seems to use a default one.
@AnimatorElisa Hmm if i’m not mistaken I believe that when you save your file for the first time, the name it will suggest is the last name you used to save a file with.
For example if I save a file with the name “my_june_animation.pclx” and I stop using Pencil2D until august then try to save a new file again, when I go to File > Save the file will be suggested to use the name “my_june_animation.pclx”
While researching this it led me to think that the save file names are being suggested by taking the “LastFilePath” property in the windows registry. So I looked into it.
DISCLAIMER: Don’t tinker with the Pencil2D registry too much, since these values are not meant to be edited by users. In the worst of cases you can delete the entire Pencil registry folder and when you start Pencil2D it will regenerate it, but be careful nonetheless.
If you go to Start > Search for “Regedit” > you’ll gain access to the windows registry editor. To access to Pencil2D’s registry properties you have to navigate to the following key:
Computer\HKEY_CURRENT_USER\SOFTWARE\Pencil\Pencil
In there you’ll find the LastFilePath key which is the one that seems to populate a new name for saved files. I tried changing this property but I would still get the same suggestion over and over so it musn’t be that or it could be that changing it directly doesn’t have an effect so probably the name is stored in the binary of the software.
Other than that using the Save As… command also prompts the LastFilePath property name of a project.
I’ll ask the developers if there’s an explicit way of changing this, so If I know anything more I’ll update this thread. 
Thanks for the insight Jose!