Sorry for the slow response. I was hoping a German reader would answer. I don’t speak German, and I’m relying on Google Translate.
First, spend some time reading the forum, and searching for similar articles. There are a few German posts similar to yours, but you’ll probably have to read some English articles too. The forums use “Discourse” rules, so a bit of reading should let you post pictures. Pictures will help us help you.
The SnapMaker Black PLA is known for being low quality. It has a lot of stringing / threads and bubbling. The test vase is printed in a single continuous line, so it won’t have those issues. Most people recommend finding a highly rated PLA on your local internet shopping site instead. I’ve been using Hatchbox, and I’m mostly happy with it.
Some stringing / threads are to be expected. The PLA oozes out when the print head is moving, and you’ll never really get rid of them. But you can improve them enough that you should be able to remove them just by running your hands over the print.
If better PLA continues to have this problem, there are a couple things to try. First, print a temperature tower (see below), and pick the temperature that has the fewest problems. This is something I do with every new spool, because it changes even with the same manufacturer and color. If it is still a problem, enable Z-Hop Retract section in the Travel. It pulls the filament back up when the print head moves so it less likely to ooze out of the nozzle.
If you’re having problems with printing tolerances, with pieces getting stuck together when they shouldn’t (That’s my interpretation of google’s translation of “Oder obejekte die vebunden und doch beweglich sind sind meistens fest ich kann es twar mit dem messer nachhelfen . Aber es sollte ja auch so gehen.”) That’s a problem for everybody. The best thing you can do is go through 3d Print Guide_Walk Through (there is temperature tower GCode linked in the guide). Calibrate your E-Steps, print test objects, and refine your prints. Once you can reliably print the benchmarks with the correct dimensions, then try your parts again. Even so, you might need to under extrude difficult parts. I’m still working to calibrate my Original so that I can print Print in Place Engine Benchmark - The Bengine by Turbo_SunShine - Thingiverse at 100% without needed a knife to make it work.