Questions & Answers about Ich habe gestern die neue Software installiert.
Since this lesson is about the un- prefix, could I say uninstalliert to mean "uninstalled"?
No. While English uses "un-" to reverse verbs like "uninstall", the German prefix un- is highly productive for adjectives and nouns, but not used to reverse verb actions. For loanwords ending in -ieren, German usually uses the prefix de-. Therefore, "to uninstall" is deinstallieren, and its past participle is deinstalliert.
Why is the past participle installiert instead of geinstalliert?
Verbs that end in -ieren (which are usually borrowed from other languages) never take the ge- prefix in the perfect tense. You just add a -t to the stem. Other common examples you have likely seen include studiert (studied) and repariert (repaired).
Why does the adjective neue just end in -e here?
This is an example of weak adjective declension. Because the definite article die already clearly marks the noun as feminine and in the accusative case (since it's the direct object), the adjective doesn't need a strong ending to show the case or gender. It simply takes the default weak ending -e.
Could I put gestern at the very beginning of the sentence?