I have to print a map in A0 paper size and also in A3. First I completed the job for the A0 size map, then I duplicated the print composer and I am changing the fonts of attribute tables and label boxes, one by one, to a smaller size for the A3 map. Is there a way to change all the fonts for every text in the print composer, at once? (QGIS 2.18)
[GIS] Change font size of all labels print composer
fontprint-composerqgisqgis-2.18text;
Related Solutions
You could also use "map units" instead of "points" to scale your labels and lines (you'll need rather huge values in most cases). This way your labels will always have a fixed size in relation to your map, and you'll be able to place them very precisely within the map canvas - no need to switch over to the composer (useful in very crowded maps).
This disadvantage is, of course, that you might not be able to read the labels in too small or large scales, because they might be either too small or too large.
The scale will inevitably effect the extent for any given area and that will be limited by the size of your paper (so an A4 sheet @ 1:50,000 scale will be approximately a half of the possible extent of an A3 sheet). Contrariwise, setting the map extent for a given area of paper will also inevitable dictate the scale. You cannot adjust one without influencing the other (which is why you have received some negative scores for this question).
You have stated that your actual extent is not as important as scale. So to resolve your dilemma, set the scale and then, with the map selected, click the 'Move item content' button (icon is a small arrow and green box, next to the 'Select/Move item' button - a large arrow).
You can now 'slide' the content of the map without changing the position of the map on the page and thereby center you map contents on your area of interest.
If the extent of the map is still not large enough at the scale you must use, then you need to increase the size of the map and that might mean splitting your map over two or more sheets and to do that effectively you can use the Atlas generator.
Best Answer
Probably a bit late to answer but for next time you can define a project variable "Label_Font" with the name of the desired font, then use data defined property font choice for labeling (with the expression @Label_Font). Once set up when you change the name of the font in your "Label_Font" variable all your label will update with the new font. You can do the same for the label size with another variable.
I haven't tested it so I have no idea if that will work but you could try to open a copy of the .qgs file in a text editor and use search and replace to change the font name, save the file then open it again in qgis