Editing question?

Hello, I’m new to creating content on TikTok…and as such, I humbly and noobly ask;

How do you merge multiple full length videos in the app to post onto my profile? My videos aren’t very long. One video is 19s, the next is 10s, followed by an 18s long video and it closes with an 11s clip.

They do merge when I select multiple videos, but not in their entirety. Somehow they’re all trimmed down to equal 20s when added up it should be about 58-60s in total.

I’ve already trimmed the videos individually but it changed nothing. Am I out of luck or is there a way? Thank you in advance!