Changing text in multiple blocks
If you are talking about AutoCAD Architecture room tags (Multi-View Blocks), and you have already revised the AutoCAD view block definition to have the desired font on the attributes therein, then you will need to run the MVBLOCK command and choose the Update command line option on the room tag instances that you want to have match the attribute font used in the current view block definition.
Are you using the out-of-the-box tools and source files? If so, are you willing to modify those?
The out-of-the-box Room Tag tool (based on US Imperial content) is set up to use the text style of the target drawing when a Room Tag is placed. That does not change the view block attribute font, however, and a use of the Update option of the MVBLOCK command will revert any selected room tags to the font/style used in the view block. But if you would rather not customize, just by setting your preferred text style current, you can get the room tags to use that text style.
If you do not want to rely on the end user to set the correct text style, you can set the tool up to use the text style as defined in the source file. In that case, you will need to edit the view block definition in the source file (the tool properties will tell you the file path and name) and then set the Attribute text style property of the tag tool to As defined by content, rather than Target drawing text style.
INSERT your source block (with the desired text style set on the attribute definitions therein) and overwrite the definition in the target file. This will not update any existing attributes; to do so, run the ATTSYNC command on that block, to force the revised attribute definitions onto existing attributes.
Attributes are separate objects "attached" to each block reference, unique for each instance. They are not automatically updated when the block definition is updated, even when there are changes to the attribute definitions in the block definition. It has always been this way. Running ATTSYNC is the means provided to force changes to existing instances of attributed blocks.
