When a compound verb is inseparable, it means that it is regarded as one, indivisible word.
An important characteristic of inseparable verbs:
inseparable verbs: the stress always lies
on the verb not on the prefix
This is a good way to distinguish it from separable verbs, where the stress lies on the prefix.
Formation of the present and simple past tense
In the present and simple past, the inseparable compound verb is subject to the normal rules: it is not divided into its elements, like the separable compound verbs, so the adverbial prefix remains attached to its verb.
Overleven (to survive):
Formation of the past participle
The past participle also behaves a bit differently: instead of the regular (ge+stem+d/t), the prepositional or adverbial prefix replaces the prefix ge-, so we get:
Adverbial prefix + stem + d/t
e.g. past participle: over+leef+d = overleefd
Recall, that we recognize the inseparable verb by its stress: it is placed on the verb, not on the prefix.
Note that the examples above give you the unstressed personal pronouns. Some pronouns change when they are stressed in a phrase: je/jij, we/wij, ze/zij (both singular and plural).