Sed replaces the last match - you need to combine everything

I would like to replace all {} with a specific line with [], but unfortunately I can only match the last occurrence of a regular expression.

I have a configuration file that has the following structure:

entry {
    id      123456789
    desc    This is a description of {foo} and was added by {bar}
    trigger 987654321
}

I have the following sed from which you can replace the last bit of "bar", but not "foo":

sed s'/\(desc.*\){\(.*\)}/\1\[\2\]/g' < filename

I bind this search to a string containing "desc", since I would not want it to replace the braces of each "entry" block.

Throughout life, I cannot figure out how to replace all occurrences.

Any help is appreciated - she studied all day and could not read more textbooks, fearing that my corneas might break.

Thank!