You didn’t tell how you “dropped some text in Arial”. I guess you selected from the Font menu in the toolbar.
This type of operation is called direct formatting and is the cause of “formatting nightmare” until you understand how Writer works.
Writer is based on styles which are ubiquitous: paragraph, character, page, frame, list. Use of styles allow for formatting automation, i.e. you concentrate on your text, not its appearance. When it comes to text, some categories interact which each other. Text is formatted as if it was composed of layers:
- the base level is controlled by paragraph styles which define the global appearance of paragraphs
- above this level, you have character styles which change aspect of selected words or sequences of characters
Of course, character styles won’t change paragraph geometry. They only change visual attributes such as font face, size, weight, colour, … or even language.
- at top, direct formatting may override everything: “geometry” as well as visual attributes
Given this hierarchy, your manual action to change font face to Arial overrides the definition in the paragraph style. Direct formatting “masks” any formatting in the lower layers.
For your peace of mind, read the Writer Guide and learn how to work with styles. Avoid direct formatting except for “exceptional” actions such as resetting list numbering, or inserting one-of-a-kind page break.
Direct formatting is provided mainly to ease Word-switchers because you can’t do otherwise in Word (it knows only of paragraph styles). With full styling, you can dramatically change the appearance of your document in a matter of minutes without the need to review text.
By the way, in Writer, the “standard” paragraph style for text is Text Body, not Default Paragraph Style. Styles are organised in a tree-like structure where styles inherit from their ancestor (except for attributes which are forced in the definition). Default Paragraph Style is the ultimate ancestor of all other styles. This is the ideal item to define your own preferences, but remember any change you make to it cascades down to all others onto the non-overridden attributes.