When components are added to a design from a library, you can choose how the styles used for pads, text, etc., on the symbol or footprint should appear in the design.
Controlling style behaviour
The setting for controlling this style behaviour is on the Design Settings dialog, accessible from the Setup menu. On the General tab, you'll see a group of radio buttons entitled "Matching Styles". Each of the three settings is described below. The best place to put your preferred setting is in the Technology file (or files) you use to create new designs. That will make sure that each design you create behaves in the same way.
By Name Only
This will ignore the actual values in the styles, and only match by the style name. Thus if you have a text item in your symbol that uses style "Title Text", it will use that style in the design regardless of its actual size. This setting may be useful for example in a pcb design if you have set the pad style sizes slightly different from the normal sizes for a particular soldering technique, and you want each new component added to use those new sizes.
By Value Only
This setting guarantees that the items added from the library come in exactly as they were saved in the library originally. You can then change styles in the design safe in the knowledge that you won't affect any new components that you add to the design afterwards.
By Name and Value
This is the preferred setting, and will match styles by both name and values. Only if the name and all values match between design and symbol will the design style be used. You can use this setting if you don't want library items to use design styles that just happen to be the right size, thus allowing you to keep 'design-only' styles separate from library item styles.