Filament that doesn’t loose it’s tension?

Anything I print that requires some tension, like something that will stretch to keep it tight on another object, always looses it’s tension over a period of days.

For example. a sunglasses visor holder I made. Fits nice and tight but will eventually get loose and fall off.(it’s winter so you can’t blame the heat)

Or the desk wire holder I made. Fit on very tight the first day, now it’s loose and slides everywhere.

I have used PLA and PETG. is this just a thing with 3D printed filaments? Or is there a magical filament my Ender 3 can print that will fix this?

THanks!